Researcher Database

Hiroyuki Munehara
Field Science Center for Northern Biosphere Aquatic Research Station Usujiri Fisheries Station
Professor

Researcher Profile and Settings

Affiliation

  • Field Science Center for Northern Biosphere Aquatic Research Station Usujiri Fisheries Station

Job Title

  • Professor

J-Global ID

Research Interests

  • 分子生態学   行動生態学   海洋生態学   魚類生態学   

Research Areas

  • Life sciences / Aquaculture

Research Activities

Published Papers

  • Takeshi Ito, Masaya Morita, Seiya Okuno, Kazuo Inaba, Kogiku Shiba, Hiroyuki Munehara, Yasunori Koya, Mitsuo Homma, Satoshi Awata
    Ecology and Evolution 12 (12) 2045-7758 2022/12
  • Hiroyuki Munehara, Kouji Togashi, Sayuri Yamada, Takushi Higashimura, Aya Yamazaki, Shota Suzuki, Takuzo Abe, Satoshi Awata, Yasunori Koya, Osamu Tsuruoka
    ICHTHYOLOGICAL RESEARCH 1341-8998 2022/09
  • Hiroyuki Munehara, Kouji Togashi, Sayuri Yamada, Takushi Higashimura, Aya Yamazaki, Shota Suzuki, Takuzo Abe, Satoshi Awata, Yasunori Koya, Osamu Tsuruoka
    ICHTHYOLOGICAL RESEARCH 1341-8998 2022/08 
    A new species of grunt sculpin, Rhamphocottus nagaakii inhabiting the northwestern Pacific, previously identified as Rhamphocottus richardsonii Gunther 1874, is described based on genetic evidence and morphological differences. The new species can be distinguished based on morphometric characters related to the head, including head length [45.3-54.6% of standard length (SL)], postorbital head length (18.8-25.5% SL) and the length of pectoral-fin base (15.8-20.7% SL), which are smaller than in R. richardsonii (53.6-60.5% SL, 26.2-31.7% SL, and 19.5-25.2% SL, respectively). Genetic differences between two species markedly exceed levels for intra-specific differences. Rhamphocottus nagaakii is considered to have arisen from a common ancestor of the two species, which probably inhabited somewhere the North Pacific Rim around the Aleutian Archipelago. During a period of cooling in the Pliocene or the Miocene, R. nagaakii and R. richardsonii became separated to the southern regions of the northwestern and northeastern Pacific, and subsequently underwent speciation.
  • Satoshi Awata, Takeshi Ito, Karen D Crow, Yasunori Koya, Hiroyuki Munehara
    Journal of fish biology 100 (1) 82 - 91 2022/01 
    In this study, the authors report the first record of egg masses deposited in solitary tunicates by the snubnose sculpin, Orthonopias triacis, from the Northeastern Pacific. Four egg masses were discovered in the tunicate Ascidia ceratodes that were genetically determined to be O. triacis. Female O. triacis had long ovipositors that allow deposition of their eggs inside the atrium of the tunicates. A comparison of host-tunicate size with ovipositor length of sculpins from the Northwestern Pacific, including the genera Furcina and Pseudoblennius, revealed that O. triacis had shorter ovipositors and spawned in the atrium of smaller species of tunicates. Ancestral state reconstruction of egg deposition in solitary tunicates using 1.86Mbp RNAseq data of 20 sculpin species from Northeastern and Northwestern Pacific revealed that this unusual spawning behaviour may have evolved convergently in different species occurring in the Northeastern vs. the Northwestern Pacific.
  • Yamazaki A., Ogino A., Munehara H.
    Journal of Fish Biology 96 (4) 1004 - 1013 0022-1112 2020/02/14 [Refereed][Not invited]
     
    Larval dispersion rather than adult migration generally leads to the worldwide expansion of fishes. Species of the genus Gymnocanthus have expanded geographically while undergoing allopatric speciation. Of this genus, while Gymnocanthus tricuspis inhabits the Arctic Ocean and surrounding area, G. herzensteini and G. intermedius occur around northern Japan. Larval early life histories of G. herzensteini and G. intermedius from northern Japan and G. tricuspis from Unalaska Island were investigated to estimate their dispersal potential during larval stages. The larval and juvenile abundances of G. herzensteini and G. intermedius were highest in May in shallow sandy bottoms below 7 m in depth, and the body sizes were 9.7-34.6 mm notochord length (NL) and/or standard length (SL) in G. herzensteini and 8.4-46.7 mm NL and/or SL in G. intermedius. Two egg masses of G. tricuspis (1.92 +/- 0.08 mm in diameter) and hatched larvae (6.20 +/- 0.19 mm NL) were collected in March. Compared with other sculpins in previous studies, the body sizes of G. herzensteini and G. intermedius at hatch are large and at settlement are small, while both hatch and settlement sizes of G. tricuspis are much larger. Counting micro-increments between the hatch check and settlement marks in G. herzensteini and G. intermedius demonstrated that the pelagic larval durations for 2 weeks with an immature body suggests that these species cannot disperse widely during the pelagic phase, while pelagic larvae of Arctic species such as G. tricuspis with long pelagic larval durations could disperse.
  • Shota Suzuki, Shota Miyake, Katsutoshi Arai, Hiroyuki Munehara
    Evolution 74 (2) 392 - 403 0014-3820 2020/02 [Refereed][Not invited]
     
    Unisexual vertebrates (i.e., those produced through clonal or hemiclonal reproduction) are typically incapable of purging deleterious mutations, and, as a result, are considered short-lived in evolutionary terms. In hemiclonal reproduction (hybridogenesis), one parental genome is eliminated during oogenesis, producing haploid eggs containing the genome of a single parent. Hemiclonal hybrids are usually produced by backcrossing hemiclonal hybrids with males of the paternal species. When hemiclonal hybrids from a genus of greenlings (Hexagrammos) are crossed with males of the maternal species, the progeny are phenotypically similar to the maternal species and produce recombinant gametes by regular meiosis. The present study was conducted to determine if the hemiclonal genome is returned to the gene pool of the maternal species in the wild. Using a specific cytogenetic marker to discriminate between such progeny and the maternal species, we observed that Hexagrammos hybrids mated with maternal and paternal ancestors at the same frequency. This two-way backcrossing in which clonal genomes are returned to the gene pool where they can undergo recombination plays an important role in increasing the genetic variability of the hemiclonal genome and reducing the extinction risk. In this way, hybrid lineages may have survived longer than predicted through occasional recombinant generation.
  • Satoshi Awata, Haruka Sasaki, Tomohito Goto, Yasunori Koya, Hirohiko Takeshima, Aya Yamazaki, Hiroyuki Munehara
    Marine Biology 166 (5) 0025-3162 2019/05 [Refereed][Not invited]
  • Yamazaki A, Nishimiya Y, Tsuda S, Togashi K, MUNEHARA Hiroyuki
    Biomolecules 9 (4) 127 - 139 2218-273X 2019 [Refereed][Not invited]
     
    Many marine species inhabiting icy seawater produce antifreeze proteins (AFPs) to prevent their body fluids from freezing. The sculpin species of the superfamily Cottoidea are widely found from the Arctic to southern hemisphere, some of which are known to express AFP. Here we clarified DNA sequence encoding type I AFP for 3 species of 2 families (Cottidae and Agonidae) belonging to Cottoidea. We also examined antifreeze activity for 3 families and 32 species of Cottoidea (Cottidae, Agonidae, and Rhamphocottidae). These fishes were collected in 2013-2015 from the Arctic Ocean, Alaska, Japan. We could identify 8 distinct DNA sequences exhibiting a high similarity to those reported for Myoxocephalus species, suggesting that Cottidae and Agonidae share the same DNA sequence encoding type I AFP. Among the 3 families, Rhamphocottidae that experience a warm current did not show antifreeze activity. The species inhabiting the Arctic Ocean and Northern Japan that often covered with ice floe showed high activity, while those inhabiting Alaska, Southern Japan with a warm current showed low/no activity. These results suggest that Cottoidea acquires type I AFP gene before dividing into Cottidae and Agonidae, and have adapted to each location with optimal antifreeze activity level.
  • Host selection and the evolution of ovipositor morphology in nine sympatric species of sculpins that deposit their eggs into tunicates or sponges
    Awata S, Sasaki H, Goto T, Koya Y, Takeshima H, Yamazaki A, MUNEHARA Hiroyuki
    Marine Biology 2019 (166) 47 - 59 2019 [Refereed][Not invited]
  • N. Sato, T. Kasugai, Y. Ikeda, H. Munehara
    Journal of Zoology 282 (3) 151 - 156 0952-8369 2018/02/01 [Refereed][Not invited]
     
    To examine the mechanism of sperm storage in Idiosepius paradoxus, here we describe aspects of the mating behavior of I. paradoxus and the morphology of the spermatozoa and the seminal receptacle after copulation. The seminal receptacle is located in the ventral portion of the buccal membrane surrounding the buccal mass, and opens inside the buccal membrane. It branches into approximately six sacs, similar in appearance to a bunch of bananas, and its wall consists of cuboidal ciliated epithelial cells (with oval nuclei) surrounded by a connective tissue. Multiple vacuoles are distributed in the bottom region of each sac. These histological and morphological characteristics differ from previous reports for loliginid squids and cuttlefish. In all except one receptacle observed in this study, sperm were stored near the bottom of each sac, and each sperm was facing the sac bottom. We observed spermatozoa in the entrance of the seminal receptacle in only one squid. These results suggest that spermatozoa were actively moving, and that sperm actively swam to the seminal receptacle. The volume of sperm in the seminal receptacles of the squid that had copulated eight times was the same as that in the squid that had copulated 29 times, which suggests that the seminal receptacle was filled after approximately eight copulation events. A squid that had copulated nine times retained a significant number of sperm in the seminal receptacle after spawning, suggesting that all of the sperm in the receptacle was not depleted after one spawning event. © 2010 The Authors. Journal of Zoology © 2010 The Zoological Society of London.
  • Gene expression of antifreeze protein in relation to historical distributions of Myoxocephalus fish species
    Yamazaki A, Nishimiya Y, Tsuda S, Togashi K, MUNEHARA Hiroyuki
    Marine Biology 2018 (165) 170 - 181 2018 [Refereed][Not invited]
  • 松原直人, 松田裕太, 赤松友成, 高橋竜三, 宗原弘幸, 安間洋樹
    海洋音響 4-5 (2) 37 - 46 2018 [Refereed][Not invited]
  • Shota Suzuki, Katsutoshi Arai, Hiroyuki Munehara
    PLOS ONE 12 (7) e0180626  1932-6203 2017/07 [Refereed][Not invited]
     
    Two types of natural hybrids were discovered in populations of three Hexagrammos species (Teleostei: Hexagrammidae) distributed off the southern coast of Hokkaido in the North Pacific Ocean. Both hybrids reproduce by hybridogenesis, in which the maternal haploid genome is transmitted to offspring without recombination and the paternal haploid genome is eliminated during gametogenesis. While natural hybrids are unisexual and reproduce hemiclonally by backcrossing with the paternal species (BC-P), artificial F-1-hybrids between the pure species produce recombinant gametes. Thus, despite having the same genome composition, the natural hybrids and the F-1-hybrids are not genetically identical. Here, to clarify the differences between both hybrids, we examined the karyotypes of the three Hexagrammos species, their natural hybrids, the artificial F-1-hybrids, and several backcrosses. Artificial F-1-hybrids have karyotypes and chromosome numbers that are intermediate between those of the parental species. Conversely, the natural hybrids differed from F-1-hybrids by having several large metacentric chromosomes and microchromosomes. Since the entire maternal haploid genome is inherited by the natural hybrids, maternal backcrosses (BC-M) between natural hybrids and males of the maternal species (H. octogrammus; Hoc) have a hemiclonal Hoc genome with large chromosomes from the mother and a normal Hoc genome from the father. However, the large chromosomes disappear in offspring of BC-M, probably due to fissuring during gametogenesis. Similarly, microsatellite DNA analysis revealed that chromosomes of BC-M undergo recombination. These findings suggest that genetic factors associated with hemiclonal reproduction may be located on the large metacentric chromosomes of natural hybrids.
  • 百田和幸, 宗原弘幸
    北大水産科学研究紀要 59 (1-2) 1 - 18 2186-1927 2017 [Not refereed][Not invited]
     
    We conducted SCUBA-based surveys of the larval and juvenile fish fauna in reef and seaweed areas in the inshore region of Usujiri, Hakodate, along the Pacific coast of southern Hokkaido, Japan, from 2011 to 2015. A total of 97 species in 9 orders and 33 families were identified based on morphological observations and DNA barcoding analyses of the Cytochrome c oxidase subunit I(COI) gene. Of these species, three specimens of the syngnathid, Urocampus nanus Gunther, 1870, three specimens of the pomacentrid, Chromis notata(Temminck and Schlegel, 1843), one specimen of the pomacentrid, Abudefduf notatus(Day, 1870), one specimen of the pomacentrid, Pomacentrus coelestis Jordan and Starks, 1901, one specimen of the tetrarogid, Hypodytes rubripinnis(Temminck and Schlegel, 1845), 20 specimens of the labrid, Halichoeres tenuispinis(Gunther, 1862), 20 specimens of the labrid, Parajulis poecileptera(Temmminck and Schlegel, 1843), one specimen of the cottid, Pseudoblennius sp. 2 and one specimen of the ostraciid Ostracion cubicus Linnaeus, 1758, represent the first records of these nine species in the study area. Of these nine species, the records for U.nanus, A.nonatus, H.rubripinnis, H.tenuispinis, P.sp.2 and O.cubicus represent the northernmost records of these six species in the Pacific Ocean.
  • 百田和幸, 宗原弘幸
    北大水産科学彙報 北海道大学大学院水産科学研究院 67 (1) 7 - 12 1346-1842 2017 [Not refereed][Not invited]
     
    Aspects of the reproductive ecology and early life history of the tubenose poacher Pallasina barbata(Steindachner,1876) were clarified based on observations on the development of eggs without artificial insemination and on morphological changes of larvae and juveniles. The reproductive mode was identified as internal gametic association, which has been reported in several cottoids. The inferred spawning periods and hatching periods were May and March, respectively, suggesting the embryonic period lasted 10 months, which is near the longest known among the Agonids. The eggs were found in the sponge Mycale adhaerens. Newly-hatched larvae were in the flexion stage, and the notochord length(NL) was 7.3mm. In the flexion larvae stage, two white spots occurred in the dorsal finfold, which have not been reported in larvae of other Agonids. Extension of the snout and protrusion of the lower jaw barbel began from 11.7mm NL at post-flexion. At 20.2mm standard length(SL), the finfold had disappeared, and all the fin ray number attained the fixed number. The scale number of bony plates reached the same number as in the adult at 28.7mm SL.
  • Naoto Matsubara, Hiroyuki Munehara, Ryuzo Takahashi, Tomonari Akamatsu, Kazuki Yamato, Ikuo Matsuo, Nobuo Kimura, Kazuyoshi Maekawa, Hiroki Yasuma
    The Journal of the Acoustical Society of America 140 (4) 3065 - 3065 0001-4966 2016/10
  • Hiroyuki Munehara, Miho Horita, Motoko R. Kimura-Kawaguchi, Aya Yamazaki
    ECOLOGY AND EVOLUTION 6 (19) 7126 - 7140 2045-7758 2016/10 [Refereed][Not invited]
     
    Two natural, hemiclonal hybrid strains were discovered in three Hexagrammos species. The natural hybrids, all of which were females that produced haploid eggs containing only the Hexagrammos octogrammus genome (maternal ancestor; hereafter Hoc), generated F-1 hybrid-type offspring by fertilization with haploid sperm of Hexagrammos agrammus or Hexagrammos otakii (paternal species; Hag and Hot, respectively). This study was performed to clarify the extent of diversification between the two hybrids and the maternal ancestor. Genealogical analysis using mtDNA revealed that all 38 Hoc/Hot hybrids formed a branch (Branch I) with 18 of the 33 Hoc/Hag hybrids. No haplotype sharing was observed with the maternal ancestor. Further, microsatellite DNA analysis suggested that the members of Branch I shared the same hemiclonal genome set. The results suggested that Hoc/Hot hybrids originated by anomalous hybridization, or "host switching," between Hoc/Hag and Hot, and not from interspecific hybridization between Hoc and Hot. The remaining 9 of 11 Hoc/Hag haplotypes and all of the 27 Hoc haplotypes were mixed within the genealogical tree, as if they had originated from multiple mutations. However, Hoc/Hag could also mate with Hoc. Although offspring from this host switch (Backcross-Hoc) have the same genome as normal Hoc, a part of their genome retains genetic factors capable of producing hemiclones. Consequently, when a descendant of a BC-Hoc hybrid mates with Hag males, a new hemiclone lineage will arise. Multiple haplotype revival through host switching from a single mutation in hybrids is another possible hypothesis for the observed mixing of Hoc/Hag haplotypes within the mtDNA genealogical tree.
  • Ang Li, Hiroyuki Munehara
    MITOCHONDRIAL DNA 26 (1) 125 - 126 1940-1736 2015/02 [Refereed][Not invited]
     
    The complete mitochondrial genome (mitogenome) sequence of Enophrys diceraus (Cottidae) was determined for the first time by primer walking methods. It was 16,976 bp in length and contains 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, and a control region (CR). Within the CR, the extended termination-associated sequence, the central conserved sequence block (CSB-F, CSB-E, CSB-D, CSB-C, CSB-B, CSB-A) and the conserved sequence block (CSB-1, CSB-2, CSB-3) were identified. This first mitogenome information among marine sculpins is expected to enrich the knowledge on phylogenetic studies of this taxon.
  • 山崎 彩, 永野優季, 菊地優, 百田和幸, 鈴木将太, 五十嵐健志, 宗原弘幸
    北大水産科学研究紀要 Faculty of Fisheries Sciences, Hokkaido University 57 (1) 1 - 24 2186-1927 2015 [Not refereed][Not invited]
     
    From 2012 to 2014 intertidal and coastal fishes were collected while SCUBA diving at Ohata, Kawauchi, Asizaki and Wakinosawa in the Shimokita Peninsula, Aomori Prefecture, northern Japan. During these surveys, 21 families, 43 genera and 51 species were collected and 7 families 7 genera and 7 species were photographed. Eleven species(Halichoeres tenuispinis, Porocottus allisi, Furcina osimae, Furcina ishikawae, Pseudoblennius cottoides, Lethotremus awae, Aptocyclus ventricosus, Chirolophis saitone, Neoclinus briyope, Parablennius yatabei, and Sagamia geneionema) were newly recorded from Ohata, 3 from kawauchi(Omobranchus elegans, Repomucenus valenciennei, and Acentrogobius virgatulus), and 1 from Ashizaki(Acentrogobius virgatulus), although they have been previously recorded from other areas of Aomori Prefecture.
  • カジカ科スイ Vellitor centropomus における雌雄の生殖腺組織と体内配偶子会合の確認
    古屋康則, 三橋直哉, 安房田智司, 伊藤岳, 宗原弘幸
    魚類学雑誌 62 (2) 21 - 131 2015 [Refereed][Not invited]
  • Noriyosi Sato, Takashi Kasugai, Hiroyuki Munehara
    ZOOLOGY 117 (3) 192 - 199 0944-2006 2014/06 [Refereed][Not invited]
     
    In cephalopods, sperm discharge is an important event not only for sperm transfer but also influencing sperm storage capacity of attached spermatangia (everted spermatophores). To investigate sperm discharge from spermatangia and the condition of naturally attached spermatangia in Japanese pygmy squid (Idiosepius paradoxus) we (i) investigated the morphology of spermatophores and spermatangia, and the process of spermatophore evagination and sperm discharge from spermatangia obtained in vitro; (ii) observed spermatangia that were naturally attached to female squids at 6, 12, 18, 24 and 48 h after copulation to investigate alterations in naturally attached spermatangia with time. The spermatophore of I. paradoxus is slender and cylindrical and consists of a sperm mass, a cement body and an ejaculatory apparatus, which is similar to those of loliginid squids. The spermatangium is fishhook-shaped, its distal end being open and narrow. After the spermatangium is formed, the sperm mass gradually moves to the open end of the spermatangium, from where sperm are released. Sperm discharge is a rapid process immediately after the beginning of sperm release, but within 5 min changes to an intermittent release of sperm. Although the volume of residual spermatozoa differed among spermatangia that were naturally attached to a single individual, the probability that spermatangia would be empty increased with time. Most naturally attached spermatangia discharged almost all of their spermatozoa within 24 h after copulation, and no spermatangia were attached to females 48 h after copulation. These results suggest that sperm transfer from the spermatangium to the seminal receptacle must occur within 24 h, and that the spermatangium functions as a transient sperm storage organ in pygmy squids. (C) 2014 Elsevier GmbH. All rights reserved.
  • Noriyosi Sato, Takashi Kasugai, Hiroyuki Munehara
    EVOLUTIONARY BIOLOGY 41 (2) 221 - 228 0071-3260 2014/06 [Refereed][Not invited]
     
    Females can express mate (or fertilisation) preferences after copulation. In the Japanese pygmy squid, Idiosepius paradoxus, in which males do not show any conspicuous pre-copulatory displays, the females remove the spermatangia attached to their bodies after copulation. In this study, we observed pre- and post-copulatory behaviours and analysed which variables associated with copulation were correlated with spermatangia removal. When females mated with larger males or copulation lasted longer female squid elongated their buccal mass after copulation and removed more spermatangia. We also investigated the effects of spermatangia removal on the retained spermatangia to predict whether cryptic female choice (CFC) influenced fertilisation success. Spermatangia removal by females had a stronger effect on the number of spermatangia retained than did the number of spermatangia ejaculated by males. These results suggest that spermatangia removal after copulation by buccal mass elongation works as a CFC in Japanese pygmy squid, and females cryptically favoured small males and fast copulation.
  • Suzanne Lydia Undap, Satoshi Matsunaga, Masato Honda, Toshio Sekiguchi, Nobuo Suzuki, Fatma Khalil, Xuchun Qiu, Yohei Shimasaki, Hironori Ando, Waka Sato-Okoshi, Tomoki Sunobe, Satoshi Takeda, Hiroyuki Munehara, Yuji Oshima
    ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 96 75 - 79 0147-6513 2013/10 [Not refereed][Not invited]
     
    In this study, we measured the accumulation of tributyltin (TBT) in wharf roach (Ligia exotica Roux) and examined the species' ability to be used for TBT biomonitoring in coastal environments. In an exposure test, wharf roach were exposed to TBT via diet for 2 d. TBT was accumulated in wharf roach, and its metabolite dibutyltin was detected. The concentrations of these compounds gradually decreased during the deputation period, but they were still detected 12 d after exposure ceased (TBT 290 +/- 140 ng/g; dibutyltin 1280 +/- 430 ng/g). The biological half-life of TBT in wharf roach was estimated to be about 4 d. In a field study conducted in 2011-2012, wharf roach were collected from 15 coastal sites in Japan and 3 sites in Manado, Indonesia. TBT was detected in both Japanese and Indonesian samples. The highest concentration of TBT was found in wharf roach collected at Bitung ferry port, Manado (57.9 +/- 16.5 ng/g), which is close to a shipyard, and the highest concentration at a Japanese site was 12.3 +/- 6.2 ng/g. Thus, we were able to detect organotins in the coastal environments by testing wharf roach, suggesting that L. exotica might serve as a good bioindicator for monitoring organotin pollution. (C) 2013 Elsevier Inc. All rights reserved.
  • Aya Yamazaki, Alexander Markevich, Hiroyuki Munehara
    MARINE BIOLOGY 160 (10) 2581 - 2589 0025-3162 2013/10 [Refereed][Not invited]
     
    Gymnocanthus is the most widely distributed genus in the family Cottidae, with six species distributed in the high-latitude area of northern hemisphere. To clarify the phylogenetic relationships and to estimate the divergence times of species in the genus, 2,548 bp of the partial sequences of the 12-16S rRNA, cytochrome oxidase subunit I and cytochrome b gene were analyzed. Our results suggest the monophyletic genus, which arose in the Aleutian Archipelago, divided into a shallow-water group and a deep-water group 8.1 million years ago (Ma). G. tricuspis of the shallow-water group firstly migrated from the Pacific to the Arctic Ocean 5.0 Ma when the Bering Strait first opened. A second migration occurred in the late Pliocene to early Pleistocene after which G. pistilliger and G. intermedius diverged 3.9 Ma. Our findings are discussed within an evolutionary and zoogeographic context.
  • Nobuya Shirai, Toshiyuki Suzuki, Michiaki Yamashita, Yoshihiro Yokoyama, Yumiko Yamashita, Michiaki Yamashita, Genta Yasunaga, Shintaro Imamura, Michiaki Yamashita, Miyuki Iwai-Shimada, Kunihiko Nakai, Hiroshi Satoh, Gi-wook Hwang, Akira Naganuma, Nobuya Shirai, Testuo Ando, Junji Wakamiya, Junji Wakamiya, Kenichirou Miyamoto, Hiroshi Satoh, Katsutoshi Arai, Akira Komaru, Hiroyuki Munehara, Kyosuke Niwa, Atsushi Hagiwara, Akira Komaru, Katsutoshi Arai, Hiroyuki Munehara
    NIPPON SUISAN GAKKAISHI 79 (5) 890 - 905 0021-5392 2013/09 [Refereed][Not invited]
  • Noriyosi Sato, Takashi Kasugai, Hiroyuki Munehara
    MARINE BIOLOGY 160 (3) 553 - 561 0025-3162 2013/03 [Refereed][Not invited]
     
    In the Japanese pygmy squid Idiosepius paradoxus, females often pick up the spermatangium using their mouth (buccal mass) after copulation. To examine whether the female I. paradoxus directly transfers sperm into the seminal receptacle via this picking behaviour, or removes the spermatangium, we conducted detailed observations of picking behaviour in both virgin and copulated females and compared the sperm storage conditions in the seminal receptacle between females with and without spermatangia picking after copulation in virgin females. In all observations, elongation of the buccal mass occurred within 5 min after copulation. However, sperm volume in the seminal receptacle was not related to spermatangia picking. Observations using slow-motion video revealed that females removed the spermatangia by blowing or eating after picking. These results suggest that picking behaviour is used for sperm removal but not for sperm transfer. Moreover, the frequency of buccal mass elongation was higher in copulated females than in virgin females, consistent with the sequential mate choice theory whereby virgin females secure sperm for fertilisation, while previously copulated females are more selective about their mate. Female I. paradoxus may choose its mate cryptically through postcopulatory picking behaviour.
  • Yasunori Koya, Yukari Koike, Rie Onchi, Hiroyuki Munehara
    ZOOLOGICAL SCIENCE 30 (2) 76 - 82 0289-0003 2013/02 [Refereed][Not invited]
     
    We found two patterns of parasitic mating behaviors by male in Japanese medaka, Oryzias latipes, in the spawning by one female and two males in the aquarium condition. In the first type of parasitic mating behavior, the unpaired male would rush toward the closely adhering female and paired male, and simultaneously perform emission behavior with close adhesion to the female (simultaneous emission). The second type of parasitic mating behavior was that the unpaired male would rush toward the female with spawned eggs hanging down from the genital pore several seconds after pair-spawning, perform emission behavior with close adhesion to the female without any pre-spawning behavior (post-spawn emission). The frequencies of "simultaneous emission" and "post-spawn emission" were 20 (19.6%) and 18 cases (17.7%), respectively, in 102 trials, and the average reproductive successes about 41% and 20%, respectively. The reproductive success of simultaneous emission was not correlated with the timing and duration of spawning behaviors of the paired/unpaired male, while the reproductive success of post-spawn emission significantly decreased as the length of time during which the paired male adhered to female increased. Observations of two consecutive spawning behaviors using same combination of two males revealed that paired males always tend to become paired males. However, the role of both males was occasionally reversed, indicating flexibility in mating tactics.
  • Noriyosi Sato, Hiroyuki Munehara
    AMERICAN MALACOLOGICAL BULLETIN 31 (1) 101 - 104 0740-2783 2013/02 [Refereed][Not invited]
     
    Idiosepius paradoxus (Ortmann, 1881) has been previously collected only in the four months from September to December at Usujiri, in northern Japan, which is considered its northern limit. Previous reports indicate that I. paradoxus is not able to overwinter at this distribution boundary. In winter 2006-2007, seawater temperatures were higher than in previous years. To investigate whether I. paradoxus overwinters in Usujiri, we collected specimens monthly and compared their occurrence pattern with seawater temperature data. In 2007, samples were collected between April and August, months in which they had not been previously collected in Usujiri. Winter seawater temperatures in 2007 were higher than in any other year. These results suggested that I. paradoxus successfully overwintered in Usujiri. However, winter water temperatures in 2008 returned to their usual lows, and specimens were not found in April. Therefore, overwintering success appeared to be temporary, and range expansion toward higher latitudes does not appear to have yet occurred.
  • Noriko Azuma, Yuta Seki, Yoshiaki Kikkawa, Tomoyuki Nakagawa, Yoko Iwata, Taku Sato, Hiroyuki Munehara, Susumu Chiba
    CONSERVATION GENETICS RESOURCES 3 (3) 529 - 531 1877-7252 2011/07 [Not refereed][Not invited]
     
    We have developed and characterized 13 novel polymorphic microsatellite markers for the Hokkai Shrimp, Pandalus latirostris, to provide an effective tool for conducting genetic studies on this species. No linkage disequilibria and no deviation from HWE were detected in these markers. In 32 individuals from Lake Notoro in Hokkaido, Japan, the number of alleles and expected heterozygosities ranged from 7 to 22 and from 0.84 to 0.95, respectively, suggesting the availability of these markers for ecological studies and conservation genetics in this species.
  • Yasunori Koya, Youichi Hayakawa, Alexander Markevich, Hiroyuki Munehara
    ICHTHYOLOGICAL RESEARCH 58 (2) 109 - 125 1341-8998 2011/04 [Refereed][Not invited]
     
    Testicular structure of 9 species and sperm head morphology of 19 species of Cottidae were observed in order to clarify relationships between morphological characteristics of the male reproductive organ and reproductive mode (copulation or non-copulation). Morphological structure of the testis was divided into the following five types based on the sperm transfer and reservoir system: (1) a non-duct type in which the sperm duct is not a distinct exterior structure, but the tube for sperm transport traverses along the testis as an interior structure; (2) an anterior duct type with distinct anterior sperm ducts traversing along the testis; (3) a posterior duct type with distinct anterior sperm ducts traversing along the dorsal hilus of testis and posterior sperm ducts extending to the rear of the testis; (4) an anterior duct posterior vesicle type with distinct anterior sperm ducts traversing along the testis, and the right and left sperm ducts fusing in the rear of testis, forming the seminal vesicle; (5) a non-duct posterior vesicle type in which sperm ducts do not accompany the testis, and the testis and seminal vesicle are connected directly or through posterior sperm ducts. It is thought that in Cottidae the non-duct type of reproductive organ is primitive, and the anterior duct type is common to all non-copulating species. The testes and accompanying seminal vesicle were seen only in copulating species. Sperm head morphology was divided into three types according to the length/width ratio: oval type a parts per thousand currency sign2, intermediate type > 2 and a parts per thousand currency sign3, and slender type > 3. The type of sperm head corresponded closely to the reproductive mode; non-copulating species had oval sperm head, and copulating species had intermediate or slender ones. These results suggest that the structure of the testis and the morphology of the sperm head evolved from testes with anterior sperm ducts and oval sperm heads to testes with an associated seminal vesicle and slender sperm heads in association with the evolution from non-copulatory to copulatory reproduction in Cottidae.
  • Sato, N, A. Sekizawa, S. Awata, H. Munehara, Y. Nakashima
    Venus 69 (3/4) 214 - 217 1348-2955 2011 [Refereed][Not invited]
  • M. R. Kimura, H. Munehara
    JOURNAL OF FISH BIOLOGY 78 (1) 112 - 126 0022-1112 2011/01 [Refereed][Not invited]
     
    Habitat use and spawning substrata were surveyed to characterize the contribution of habitat divergence to reproductive isolation in greenling Hexagrammos species. The spawning substrata and microhabitat in breeding territories differed amongst the three Hexagrammos species studied: H. octogrammus, H. agrammus and H. otakii used small red algae, surfgrass and bryozoans, respectively, as spawning substrata, and breeding territories were established in areas where those substrata were abundant. In contrast, non-territorial individuals were observed in a comparatively wider range of habitats than conspecific territories. Consequently, the distributions of non-territorial individuals of the three species partially overlapped. Since hybrids have been frequently collected, the difference in spawning substrata and the subsequent microhabitat divergence in breeding territories do not prevent females from encountering males of other species. Thus, in addition to habitat divergence, other factors such as behavioural differentiation may be needed to complete premating reproductive isolation amongst these three Hexagrammos species. (C) 2010 The Authors
  • N. Sato, T. Kasugai, Y. Ikeda, H. Munehara
    JOURNAL OF ZOOLOGY 282 (3) 151 - 156 0952-8369 2010/11 [Refereed][Not invited]
     
    To examine the mechanism of sperm storage in Idiosepius paradoxus, here we describe aspects of the mating behavior of I. paradoxus and the morphology of the spermatozoa and the seminal receptacle after copulation. The seminal receptacle is located in the ventral portion of the buccal membrane surrounding the buccal mass, and opens inside the buccal membrane. It branches into approximately six sacs, similar in appearance to a bunch of bananas, and its wall consists of cuboidal ciliated epithelial cells (with oval nuclei) surrounded by a connective tissue. Multiple vacuoles are distributed in the bottom region of each sac. These histological and morphological characteristics differ from previous reports for loliginid squids and cuttlefish. In all except one receptacle observed in this study, sperm were stored near the bottom of each sac, and each sperm was facing the sac bottom. We observed spermatozoa in the entrance of the seminal receptacle in only one squid. These results suggest that spermatozoa were actively moving, and that sperm actively swam to the seminal receptacle. The volume of sperm in the seminal receptacles of the squid that had copulated eight times was the same as that in the squid that had copulated 29 times, which suggests that the seminal receptacle was filled after approximately eight copulation events. A squid that had copulated nine times retained a significant number of sperm in the seminal receptacle after spawning, suggesting that all of the sperm in the receptacle was not depleted after one spawning event.
  • Karen D. Crow, Hiroyuki Munehara, Giacomo Bernardi
    MOLECULAR ECOLOGY 19 (10) 2089 - 2105 0962-1083 2010/05 [Refereed][Not invited]
     
    Sympatric speciation has been contentious since its inception, yet is increasingly recognized as important based on accumulating theoretical and empirical support. Here, we present a compelling case of sympatric speciation in a taxon of marine reef fishes using a comparative and mechanistic approach. Hexagrammos otakii and H. agrammus occur in sympatry throughout their ranges. Molecular sequence data from six loci, with complete sampling of the genus, support monophyly of these sister species. Although hybridization occurrs frequently with an allopatric congener in an area of slight distributional overlap, we found no F(1) hybrids between the focal sympatric taxa throughout their coextensive ranges. We present genetic evidence for complete reproductive isolation based on SNP analysis of 382 individuals indicating fixed polymorphisms, with no shared haplotypes or genotypes, between sympatric species. To address questions of speciation, we take a mechanistic approach and directly compare aspects of reproductive isolation between allopatric and sympatric taxa both in nature and in the laboratory. We conclude that the buildup of reproductive isolation is strikingly different in sympatric vs. allopatric taxa, consistent with theoretical predictions. Lab reared hybrids from allopatric species crosses exhibit severe fitness effects in the F(1) or backcross generation. No intrinsic fitness effects are observed in F(1) hybrids from sympatric species pairs, however these treatments exhibited reduced fertilization success and complete pre-mating isolation is implied in nature because F(1) hybrid adults do not occur. Our study addresses limitations of previous studies and supports new criteria for inferring sympatric speciation.
  • Sperm allocation pattern during a reproductive season in the copulating marine cottoid species, Alcichthys alcicornis.
    Munehara, H, H. Murahana
    Environ. Biol. Fish. 83 371 - 377 2010 [Refereed][Not invited]
  • Motoko R. Kimura, Hiroyuki Munehara
    ECOLOGICAL RESEARCH 25 (1) 41 - 50 0912-3814 2010/01 [Refereed][Not invited]
     
    In the coastal areas of Japan, three species of greenling (Hexagrammos spp.) can hybridize. In a natural reef setting we showed that Hexagrammos agrammus and H. octogrammus established their breeding territories in a shallow area where seaweed was abundant, whereas H. otakii established breeding territories in a deep area that was sparsely covered with seaweed. This difference in habitat use resulted in H. otakii being distributed separately from the other two species, thereby reducing the potential for hybridization. However, all the three species co-occurred in an artificial area near a breakwater. This area is characterized by steep slopes and complex stacked concrete structures, which create a mosaic-habitat consisting of a shallow environment with seaweed and a deep environment with sparse seaweed, allowing the three species to breed within a single area. Our results suggest that man-made structures can create an artificial mosaic-habitat that can disrupt habitat isolation and promote hybridization between species.
  • Satoshi Awata, Motoko R. Kimura, Noriyosi Sato, Keita Sakai, Takuzo Abe, Hiroyuki Munehara
    ICHTHYOLOGICAL RESEARCH 57 (1) 16 - 23 1341-8998 2010/01 [Refereed][Not invited]
     
    The reproductive behaviour of the Japanese ornate dragonet (Callionymus ornatipinnis) was studied at the northernmost limit of its distribution at Usujiri in southern Hokkaido, Japan. Field observations confirmed that C. ornatipinnis reproduced at Usujiri, and this is the first detailed description of the reproductive behaviour of C. ornatipinnis. Males were observed to swim continuously in a sandy area where females were abundant, persistently approaching females and performing courtship displays. Courtship behaviour consisted of males spreading their fins in front of females. If a female accepted a male for spawning, the pair would then ascend upward 0.7-1.2 m from the sandy bottom and release their pelagic eggs. Spawning, which occurred daily at dusk for approximately 1 h and ceased when it became dark, was related to water temperature and was only observed when water temperature exceeded 19A degrees C. The breeding season of this species at Usujiri spanned only the month of September, which is considerably shorter than that of other dragonet species inhabiting temperate waters. The short breeding season was probably attributed to the fact that the water temperature at Usujiri only exceeds 19A degrees C in the month of September.
  • 佐藤成祥, 宗原弘幸
    ちりぼたん 日本貝類学会 40 (3) 138 - 144 0577-9316 2010 [Refereed][Not invited]
  • Masanori Kohda, Dik Heg, Yoshimi Makino, Tomohiro Takeyama, Jun-ya Shibata, Katsutoshi Watanabe, Hiroyuki Munehara, Michio Hori, Satoshi Awata
    PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES 276 (1676) 4207 - 4214 0962-8452 2009/12 [Refereed][Not invited]
     
    Theories suggest that, in cooperatively breeding species, female control over paternity and reproductive output may affect male reproductive skew and group stability. Female paternity control may come about through cryptic female choice or female reproductive behaviour, but experimental studies are scarce. Here, we show a new form of female paternity control in a cooperatively polyandrous cichlid fish (Julidochromis transcriptus), in which females prefer wedge-shaped nesting sites. Wedge-shaped sites allowed females to manipulate the siring success of the group member males by spawning the clutch at the spot where the large males were just able to enter and fertilize the outer part of the clutch. Small males fertilized the inner part of the clutch, protected from the large aggressive males, leading to low male reproductive skew. Small males provided more brood care than large males. Multiple paternity induced both males to provide brood care and reduced female brood care accordingly. This is, to our knowledge, the first documented case in a species with external fertilization showing female mating behaviour leading to multiple male paternity and increased male brood care as a result.
  • T. Takahashi, K. Watanabe, H. Munehara, L. Rueber, M. Hori
    MOLECULAR ECOLOGY 18 (14) 3110 - 3119 0962-1083 2009/07 [Refereed][Not invited]
     
    Divergent natural selection is thought to play a vital role in speciation, but clear, measurable examples from nature are still few. Among the many possible sources of divergent natural selection, predation pressure may be important because predators are ubiquitous in food webs. Here, we show evidence for divergent natural selection in a Lake Tanganyika cichlid, Telmatochromis temporalis, which uses burrows under stones or empty snail shells as shelters. This species contains normal and dwarf morphs at several localities. The normal morph inhabits rocky shorelines, whereas the dwarf morph invariably inhabits shell beds, where empty snail shells densely cover the lake bottom. Genetic evidence suggested that the dwarf morph evolved independently from the normal morph at two areas, and morphological analysis and evaluation of habitat structure revealed that the body sizes of morphs closely matched the available shelter sizes in their habitats. These findings suggest that the two morphs repeatedly evolved through divergent natural selection associated with the strategy for sheltering from predators.
  • Hiroyuki Munehara, Yoshiki Tanaka, Tomoyuki Futamura
    ESTUARINE COASTAL AND SHELF SCIENCE 83 (3) 371 - 377 0272-7714 2009/07 [Refereed][Not invited]
     
    A new sledge net system using propulsion vehicles has been developed to sample more efficiently the demersal juveniles of marine organisms. A net attached to a sledge maneuvered by a SCUBA diver who uses operating switches on a steering handle to adjust the altitude of the sledge and the position of the tickler chains to ensure that the footcloth of the mouth of the net remains in constant contact with the bottom surface. Video camera, flow meter, compass, and dive computers are positioned on the sledge net in the view of the diver. Given that the system can attain speeds of 70 cm s(-1), the net can be employed to capture highly mobile fish. Unlike most boat-based net sampling methods, the use of propulsion vehicles means that there are no sound or vibration disturbances due to the boat and tow ropes typically used to maneuver these types of sampling nets. Marine fauna was collected at monthly intervals over a two-year period in a sampling area along the southern coast of Hokkaido, Japan. A total of 2641 specimens comprising 61 species and including five species which were the first records for the region were collected. These findings suggest that the new sledge net system employing propulsion vehicles was effective for sampling demersal juveniles, particularly in situations where sledge nets towed by boats or push nets cannot be deployed. (C) 2009 Elsevier Ltd. All rights reserved.
  • Noriyosi Sato, Satoshi Awata, Hiroyuki Munehara
    ICES JOURNAL OF MARINE SCIENCE 66 (5) 811 - 815 1054-3139 2009/06 [Refereed][Not invited]
     
    The distribution of aquatic animals is limited by water temperature. However, little is known about migration patterns, overwintering, and reproduction at the extremities of their distribution. To investigate the sexual maturation of Japanese pygmy squid (Idiosepius paradoxus) and their ability to survive during winter at the northern limits of their distribution, we collected samples monthly at Usujiri in northern Japan and carried out experiments on low-temperature tolerance. Squid were collected during 4 months in autumn and early winter. In autumn, all squid were large and sexually mature, and many egg masses were found on the surface of seagrass, whereas in early winter, only small immature squid were collected. A warm north-flowing current reached the Usujiri area during autumn, so the squid were likely transported by the current and some of the small squid were recruits that hatched there. Field data and the results of experiments on tolerance of the species to low temperatures showed that it cannot survive at the low temperatures around Usujiri in winter. The migration pattern of I. paradoxus may differ from the traditional pattern for marine resources, where young fish are transported passively and do not reproduce at the extremities of their distribution.
  • 田中善規, 鶴岡理, 二村智之, 宗原弘幸
    北大水産科学研究彙報 北海道大学大学院水産科学研究院 = Research Faculty of Fisheries Sciences, Hokkaido University 59 (3) 73 - 80 1346-1842 2009 [Not refereed][Not invited]
     
    One specimen of syngnathid, Hippocampus mohnikei (Bleeker, 1853), eight specimens of callionymid, Repomucenus curvicornis (Valenciennes, 1837), two specimens of callionymid, Repomucenus valenciennei (Temminck and Schlegel, 1843), 12 specimens of paralichthyid, Tarphops oligolepis (Bleeker, 1858), and 17 specimens of monacanthid, Rudarius ercodes (Jordan and Fowler, 1902) were collected from inshore Usujiri, the Pacific coast of southern Hokkaido, Japan. These specimens of H. mohnikei, R. valenciennei, T. oligolepis, and R. ercodes represent the northernmost records of these species in the Pacific Ocean, and these of R. curvicornis represent the first records of these species from the study area.
  • 鶴岡理, 山中智之, 阿部拓三, 武藤文人, 宗原弘幸, 矢部衛, 仲谷一宏
    北大水産科学研究彙報 北海道大学大学院水産科学研究院 = Research Faculty of Fisheries Sciences, Hokkaido University 58 (3) 43 - 50 1346-1842 2009 [Not refereed][Not invited]
     
    A holocentrid Ostichthys japonicus (Cuvier, 1829), a platycephalid Platycephalus sp., a cottid Icelus sekii Tsuruoka, Munehara and Yabe, 2006, an agonid Bothragonus occidentalis Lindberg, 1935, and a stichaeid Lumpenopsis pavlenkoi Soldatov, 1916 were collected from off Usujiri, Hakodate, Hokkaido, northern Japan, the western North Pacific. Ostichthys japonicus was previously recorded from the south of Aomori Prefecture and further southern waters; thus present report represents the northern-most record of the species. Platycephalus sp. and B. occidentalis were known only by pelagic juveniles from off Usujiri. Hence, we report the first records of adults of these species from this waters. As I. sekii was previously known only from its type locality, off Rausu and Urakawa, Hokkaido, present report is the second and the southern-most records of this species. Lumpenopsis pavlenkoi has been collected from Peter the Great Bay, Okhotsk coast of Hokkaido and the waters around the Kamchatka Islands, thus present report represents southern-most record of this species in the Pacific Ocean.
  • Noriyosi Sato, Takashi Kasugai, Hiroyuki Munehara
    JOURNAL OF THE MARINE BIOLOGICAL ASSOCIATION OF THE UNITED KINGDOM 88 (2) 391 - 394 0025-3154 2008/03 [Refereed][Not invited]
     
    Growth increments in statoliths of Idiosepius paradoxus were observed for aging analysis. The rate of increment formation was examined by staining the statoliths with tetracycline at 5-14 d intervals. In 6 of 16 specimens, increments formed daily, but in the other specimens, increments formed less than one per day. The maximum number of increments observed in males and females were more than 150 and 140, respectively, suggesting a life span Of >= 150 and >= 140 d. During the cool season (from November to April), the dorsal mantle length (DML) and the number of increments gradually increased. Specimens collected in June showed bi-modal patterns in DML and the number of increments. Only small specimens were collected from August to October. These results suggest that two generations alternately occurred in the cool season and in the warm season.
  • Y. Hayakawa, E. Takayama-Watanabe, A. Watanabe, M. Kobayashi, H. Munehara, K. Onitake
    ZYGOTE 15 (4) 285 - 293 0967-1994 2007/11 [Refereed][Not invited]
     
    Polymorphism of sperm is considered to be significant for the reproductive strategy in some animal species. The phenomenon is thought to occur in the species-specific stage of spermatogenesis, but how the identical germ cells are differentiated towards polymorphic sperm remains unknown. We here performed a germ cell culture in the cottoid fish, Hemilepidotus gilberti, whose sperm exhibit dimorphism with fertilizable eusperm and unfertilizable parasperm. In the culture, germ cells, which were obtained with an identical morphology, a spherical shape of 5-7 mu m in diameter, differentiated into smaller spherical cells with a single nucleus, a moving flagellum and localized mitochondria. In addition, large retroflex-shaped cells with two elongated nuclei were also observed in the cell culture. Germ cells that had each morphological feature were histologically also observed in some cysts of the spermatogenetic testis, suggesting that the former type of cell corresponded to developing eusperm and the latter corresponded to developing parasperm. When BrdU was incorporated into germ cells in the culture, it was detected in both cells with eusperm-like and those with parasperm-like morphologies. These findings suggest that DNA-duplicating spermatocytes are potent to autonomously progress a part of spermatogenesis to form dimorphic sperm.
  • Jiro Nagao, Hiroyuki Munehara
    JOURNAL OF CRUSTACEAN BIOLOGY 27 (4) 565 - 569 0278-0372 2007/11 [Refereed][Not invited]
     
    The effects of preventing female helmet crabs, Telmessus cheiragonus from mating during one breeding season on egg production and egg viability were assessed by investigating the egg clutches of the females isolated from males. A total of 38 females and 18 males were collected in April before the mating peak in 1996 and 1997 in the sublittoral zones of Usujiri, southern Hokkaido, Japan. Eighteen females were held together with 18 males (mating group) and 20 females were isolated from males (non-mating group) during about 7 months of captivity. Subsequently, 11 females of the mating group molted, copulated and produced an egg clutch. and 10 females of the non-mating group melted and spawned without mating. Egg clutch weight and egg diameter did not differ significantly between these two groups. There was also no significant difference in the percentage of viable eggs in an egg Clutch between the groups. These results show that preventing female T. cheiragonous from mating during one breeding season has no effect on either clutch size or % viable eggs in a clutch. Sperm storage over one mating season in this species may be advantageous because it allows inultiparous females, especially larger ones which Could molt and copulate less frequently, to ensure their eggs will be fertilized.
  • Karen D. Crow, Hiroyuki Munehara, Ziyusei Kanamoto, Andrey Balanov, Dmitriy Antonenko, Giacomo Bernardi
    BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY 91 (1) 135 - 147 0024-4066 2007/05 [Refereed][Not invited]
     
    Hybridization and introgression are antagonistic to the process of speciation. If hybrids are viable and backcross, introgression will slow or prevent the evolution of reproductive isolation between populations. If species hybridize upon secondary contact, introgression will ultimately erode species boundaries. If hybridization is rampant and gene flow is high, the proportion of hybrids will approach values expected with random mating, and introgression will overcome species boundaries, homogenizing populations. Alternatively, if species are genetically distinct, the proportion of hybrids would be significantly less than expected with random mating, gene flow would be interrupted by selection against hybrids, and inviability or sterility of F-1 hybrids or backcrosses would be expected. Here, we investigate a system with characteristics expected by both of these opposing scenarios. Hybridization occurs between three species of reef fishes in the genus Hexagrammos at unexpected high frequencies in a zone of distributional overlap. Backcrossed individuals are detected, indicating F-1 hybrids are viable and capable of reproducing. Yet, these species are genetically distinct at multiple loci. To study this apparent paradox, we estimate the relative proportions of hybrids, patterns of symmetry, inviability, and cytonuclear disequilibria using one mitochondrial and two nuclear markers. We invoke selection against hybrids, at various life history stages, in the maintenance of species boundaries in this system. (c) 2007 The Linnean Society of London.
  • Takuzo Abe, Hiroyuki Munehara
    ICHTHYOLOGICAL RESEARCH 54 (2) 137 - 144 1341-8998 2007/05 [Refereed][Not invited]
     
    Characteristics of the structure and function of male reproductive organs in the copulating sculpin Radulinopsis taranetzi were investigated based on histological observations. The male reproductive organs comprised three parts: a pair of testes, a seminal vesicle, and a penis. Germinal cells matured in cysts located in the small seminal lobules. Asynchronous spermatogenesis advanced rapidly from the posterior to the anterior region of the testes. After sperm matured in the posterior part of the testes, the seminiferous epithelium of the seminal lobules synthesized and secreted eosinophilic fluid that showed a positive periodic acid-Schiff (PAS) reaction into the seminal lobules. Spermatozoa excreted from the posterior part of the testes were stored together with the secretion in the seminal vesicle and showed no activity in the seminal fl uid. Histological observations throughout the year suggest that the fl uid is secreted and spermatozoa are stored in the seminal vesicles during February to July, which is presumably when mating occurs. The importance of testicular maturation and the secretion of eosinophilic fl uid during this long reproductive period is also discussed.
  • Motoko R. Kimura, Takashi Yanagimoto, Hiroyuki Munehara
    AQUATIC BIOLOGY 1 (2) 187 - 194 1864-7790 2007 [Refereed][Not invited]
     
    Hybridization has been frequently observed among 3 species of greenlings (genus Hexagrammos) common in waters off Japan. In order to estimate the frequency of hybridization events from egg masses collected from male territories, efficient maternal identification of numerous egg masses is required. A novel streamlined approach for maternal identification of 3 Hexagrammos spp. was developed using multiplex amplified product length polymorphism (APLP) analysis of the mitochondrial. cytochrome b (Cytb) and the 12S and 16S ribosomal RNA (12-16S rRNA) regions. Concurrent use of species-specific primer sets permits the amplification of different-sized PCR products, diagnosing each species through one procedure of PCR in a single reaction tube. The APLP method produced more rapid, reliable, and cost-efficient species identifications compared to those from an established restriction fragment length polymorphism (RFLP) protocol.
  • Youichi Hayakawa, Makito Kobayashi, Hiroyuki Munehara, Akihiko Watanabe, Kazuo Onitake
    RAFFLES BULLETIN OF ZOOLOGY supplement 14 29 - 35 0217-2445 2007/01 [Refereed][Not invited]
     
    The production of non-fertile parasperm along with fertile eusperm during spermatogenesis occurs widely in animals. The parasperm of some invertebrates are known to promote eusperm fertilization. Parasperm are also produced in some species of colloid fish. This study showed that the production of parasperm without eusperm and vice versa does not occur during spermatogenesis in Gilbert's Irish lord, Hemilepidotus gilberti. Gonadosomatic indices (gonad weight / body weight with gonads x 100), which represent the gonad investment of each male, increased approximately four months prior to the spawning season, corresponding to a spur in the development of eusperm and parasperm. Both sperms may have differentiated from the same spermatocytes and electron microscopy has proven that the spermatids that become eusperm and parasperm were connected by intercellular bridges in a cyst. In the present study, the development of parasperm of H. gilberti in relation to its functions on sperm competition is also discussed.
  • S Awata, D Heg, H Munehara, M Kohda
    BEHAVIORAL ECOLOGY 17 (3) 372 - 379 1045-2249 2006/05 [Refereed][Not invited]
     
    Cooperatively breeding animals, in which helpers may participate in reproduction with dominant breeders, are ideal species for examining intraspecific variation in testis size because they often exhibit both monogamous breeding (low risk of sperm competition) and polyandrous breeding (high risk) within a population. However, little is known about testis investment as a result of sperm competition in these animals. The substrate-brooding cichlid fish Julidochromis ornatus has a cooperatively breeding system, in which some males mate monogamously and other males reproduce as dominant breeders or helpers within cooperatively breeding groups, in which male helpers frequently sire young. We examined the relationship between testis investment and male social status in relation to the risk of sperm competition. As predicted from sperm competition models, in groups with male helpers, both the male breeders and the male helpers invested more in testes mass, compared to breeding males without male helpers. We also found a positive relationship between the testes mass of male breeders and their male helpers, suggesting that males increase their investment in reproductive capability under the risk of sperm competition. Sperm competition models also predict that larger testes are associated with increased siring success. Our paternity analysis supported this prediction; we found a positive relationship between testis investment by male helpers and the number of offspring they sired.
  • O Tsuruoka, H Munehara, M Yabe
    ICHTHYOLOGICAL RESEARCH 53 (1) 47 - 51 1341-8998 2006/02 [Refereed][Not invited]
     
    A new cottid species, Icelus sekii, is described on the basis of six specimens collected from off Rausu and Urakawa, Hokkaido Island, Japan. This species is distinguished from its congeners by the following combination of characters: supraocular and parietal spines absent; nuchal spine obscure; uppermost preopercular spine unbranched; no scales between dorsal scale row and lateral line scale row, and no scales below lateral line scale row; supraocular, parietal, and nuchal cirri present; five dark brown saddles dorsolaterally; anal fin rays 13; pectoral fin rays 15; vertebrae 12 + 24-25 = 36-37. Icelus sekii can be mature at the smallest size among the species of Icelus. As a secondary sexual character, the male holotype has unique ensiform flaps on the distal tips of the first dorsal fin.
  • 伊藤欣吾, 柳本卓, 岩田容子, 宗原弘幸, 桜井泰憲
    日本水産学会誌 72 (5) 905 - 10 2006 [Refereed][Not invited]
  • 鶴岡理, 阿部拓三, 宗原弘幸, 矢部衛
    魚類学雑誌 53 (1) 89 - 93 2006 [Refereed][Not invited]
  • S Awata, H Munehara, M Kohda
    BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY 58 (5) 506 - 516 0340-5443 2005/09 [Refereed][Not invited]
     
    It is suggested that some fish of the genus Julidochromis, substrate-brooding Tanganyikan cichlids with biparental care, breed cooperatively with helpers. We studied the social system of J. ornatus in the wild and analysed genetic parentage using microsatellites. Within the studied population three patterns of social system were identified: monogamous pairs (61%, 44 of 72 groups), pairs with helpers (29%, 21), and polygamous harems with helpers (controlled by either a large female or large male owner; 10%, 7). In cooperatively breeding groups, the number of helpers at each nest ranged from 1 to 6 (median 1), and male helpers were more numerous than female helpers. In both sexes, the body size was different among individuals of different social status (harem owner > breeder > helper). Helpers and harem owners of both sexes exhibited brood defence although its frequency was low. The molecular analysis revealed that (1) the helpers were mostly unrelated to dominant breeders, (2) many helpers of both sexes contributed genetically to the next generations, (3) male helpers had high siring success (41 % of young in total), and (4) large young unrelated to group members were detected at 30% of observed nests, which may be due to breeder (or helper) replacements and immigration of young. We discuss the implications of these results for understanding the complex social system of this species, especially the low reproductive skew in comparison with other cooperatively breeding cichlids.
  • T. Abe, H. Munehara
    Journal of Fish Biology 67 (1) 201 - 212 0022-1112 2005/07 [Not refereed][Not invited]
     
    The fertilization mode, and spawning and egg-care behaviours of the sculpin Radulinopsis taranetzi were investigated in the laboratory. Embryonic development began only after the eggs came into contact with sea water. Females spawned c. 1000 eggs and covered them with sand using their pectoral and caudal fins. Unlike other cottids, the females guarded the egg masses after spawning. During the parental period, the supramaxillary lamina and mandibular lamina of females extended to form a disc-like structure, which was used to 'suck' water from near the surface of the egg mass. The frequency and duration of this 'sucking' behaviour increased gradually until hatching, which occurred after 23-26 days at 8°C. The oxygen consumption of the embryos was positively related to the 'sucking' activity. All females in this study spawned only once during the spawning season, in contrast with the paternal-care copulating cottids, which are multiple spawners. © 2005 The Fisheries Society of the British Isles.
  • R Katoh, H Munehara, M Kohda
    ZOOLOGICAL SCIENCE 22 (5) 555 - 561 0289-0003 2005/05 [Not refereed][Not invited]
     
    Telmatochromis temporalis is a bi-parental substrate brooding cichlid endemic to Lake Tanganyika. Paired males were always larger than their mates and had territories around nests against conspecific males. However, males smaller than the paired females were found in 18% of the nests. Here we report a reproductive tactic of these small males. The small males had as heavy gonads as paired males, and the gonad somatic index (GSI) of the small males was much higher than that of the latter. The examinations of the paternity and maternity using microsatellite-DNA as a genetic marker revealed that the small males were not genetically related to the pair members, and sired some young in 3 of 5 nests. These small males did not guard the broods, suggesting that they are likely to perform reproductive parasitism as sneakers. Paired males could not enter their spawning nests due to their large size, which made it difficult to chase out sneakers once they entered the nest. Some males as small as the sneakers were found outside the territories of paired males, and their gonads were quite small. Circumstantial evidence suggests that small males have two alternative investment patterns: investing in gonad to be sneakers, and investing in growth to probably be territorial males.
  • Y Iwata, H Munehara, Y Sakurai
    MARINE ECOLOGY PROGRESS SERIES 298 219 - 228 0171-8630 2005 [Not refereed][Not invited]
     
    The mating behavior of captive Loligo bleekeri and the paternity of the resulting progeny were examined based on behavioral observations and genetic analyses. In this species, there are 3 mating behaviors (male-parallel, head-to-head, and extra-pair), and 2 sperm storage sites in females (seminal receptacle and the opening of the oviduct), which suggest that sperm competition occurs. All 3 mating behaviors were observed, and females mated often with different males, resulting in multiple paternity within 3 of the 4 broods examined. In each brood, the male to mate last and frequently before the female spawned fertilized the most eggs (87 to 100%). A sneaker male that mated by extra-pair copulation sired 8.5% of the eggs in a brood. Some eggs were fertilized by sperm received before the start of the study, indicating that sperm can be stored for at least several days before a spawning. In the broods with multiple paternity, the paternity patterns differed among egg capsules. Male competition was more intense between similar-sized males than between different-sized males, but body size did not affect the copulative success in the male-parallel position. We found multiple mating and multiple paternity in L. bleekeri. Paternity rates differed depending on the complex of factors, mating position, timing, frequency and duration. Alternative reproductive behaviors would change these factors and lead to different paternity rates.
  • Y. Hayakawa, H. Munehara
    Journal of Fish Biology 64 (6) 1530 - 1539 0022-1112 2004/06 [Not refereed][Not invited]
     
    Euspermatozoa and paraspermatozoa of a copulatory (internal insemination with external sperm transfer) cottoid fish Blepsias cirrhosus were observed ultrastructurally. Euspermatozoa of B. cirrhosus consisted of an acrosome-less, thin, disk-like sperm head (1.6-2.0 μm in length and 1.3-1.6 μm in width), a long middle picee, and a long flagellum (c. 30 μm). Aberrant spermatids, which were rich in cytoplasm and possessed two nuclei, occurred in testicular lobules. They were also observed in semen and were round (5.0-5.3 μm in diameter) and biflagellate, suggesting that they are released along with euspermatozoa at ejaculation. The nuclei of aberrant spermatids developed into masses of highly electron-dense globules. Judging from their form, nuclear condition, and connection with normal spermatids by intercellular bridges during spermiogenesis, aberrant spermatids of B. cirrhosus are considered hyperpyrenic paraspermatozoa formed by incomplete cytokinesis at the second meiotic division. © 2004 The Fisheries Society of the British Isles.
  • 早川洋一, 秋山良, 宗原弘幸
    魚類学雑誌 51 (1) 33 - 42 2004 [Refereed][Not invited]
  • J Nagao, H Munehara
    FISHERIES SCIENCE 69 (6) 1200 - 1208 0919-9268 2003/12 [Not refereed][Not invited]
     
    To clarify the annual testicular maturation cycle in the helmet crab Telmessus cheiragonus, seasonal histological changes of the testis and occurrence of grasping pairs and recently copulated females with fresh sperm plugs were investigated. The testis was composed of seminiferous ducts with many testicular lobules. Development of the lobules was divided into six stages (spermatogonia proliferation, first spermatocyte, reduction division, spermatid, spermiogenesis and free sperm stage) based on the spermatogenic phase of the germ cells in each lobule. The mean percentage of the lobules during each stage was calculated every 1-3 months. Developed lobules occurred with a high percentage throughout the year except in June when developing lobules predominated. Grasping pairs and females with fresh sperm plugs were collected during April-July with a peak in May-June. These results suggest that the males have testis with many developing lobules in June when they are active for mating. Newly formed spermatozoa may be stored in the testis and the vas deferens until the next mating season after June, as the spermatozoa may not have an opportunity to fertilize eggs until the next season and there is no sign of spermatozoa absorption in the testis.
  • Y Hayakawa, H Munehara
    JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY 295 (2) 245 - 255 0022-0981 2003/11 [Not refereed][Not invited]
     
    To investigate causes of anomalous development of embryos facultatively fertilized in the ovary of a non-copulatory oviparous fish Hemilepidotus gilberti (Scorpaeniformes: Cottdae), dissolved oxygen (DO) concentrations were measured in ovaries of copulatory oviparous (Alcichthys alcicornis, Bero elegans), non-copulatory oviparous (H. gilberti, Hexagrammus otakii), and viviparous (Sebastes taczanowskii, Zoarces elongatus) fishes. DO concentrations changed during vitellogenesis and ovulation cycles, and also before and after ovulation. DO concentrations in the ovary of H. gilberti and H. otakii at ovulation were 0.27 +/- 0.03 and 0.15 +/- 0.03 mg O-2 1(-1), respectively, whereas in A. alcicornis and B. elegans, the concentrations were 0.47 +/- 0.08 and 0.20 +/- 0.06 mg O-2 1(-1), respectively. In the ovaries of intralumenal gestation viviparous fishes, S. taczanowskii and Z. elongatus, DO concentration was from 0.01 to 0.11 mg O-2 1(-1). The average DO concentration during the artificial pregnancy of A. alcicornis was 0.97 +/- 0.19 mg O-2 1(-1), but all embryos showed deformity. DO concentrations recorded in oviparous fishes in this study were lower than the oxygen level at which most oviparous fish embryos exhibit retardation or death, and it probably caused the anomalous embryonic development. In contrast, the normal development of viviparous fish embryos at low oxygen level was attributed to the specialized structure of ovary, e.g. the dual arterial system to supply the developing embryos with the respiratory demands in Sebastes. (C) 2003 Elsevier B.V. All rights reserved.
  • Y Iwata, H Munehara, Y Sakurai
    MOLECULAR ECOLOGY NOTES 3 (3) 392 - 393 1471-8278 2003/09 [Not refereed][Not invited]
     
    Loligo bleekeri has a long spawning season and the size of mature males changes during the season: dimorphic (large/small) early in the spawning season and monomorphic (small) later in the spawning season. To understand how copulatory behaviours relate to the dimorphism, we developed five polymorphic microsatellite loci in L. bleekeri. The level of polymorphism ranged from 10 to 22 alleles with expected heterozygosities ranging from 0.79 to 0.93, suggesting that the novel polymorphic loci should be useful for parentage analysis of L. bleekeri.
  • Munehara, H, A.I. Markevich
    Bull. Fish. Sci. Hokkaido Univ 北海道大学 54 (3) 67 - 72 1346-1842 2003 [Not refereed][Not invited]
  • Sunobe, T, Munehara, H
    J Ethol. 21 (2) 87 - 92 0289-0771 2003 [Refereed][Not invited]
     
    Mating system and parental behavior of ten monogamous pairs and two polygynous groups of the Tanganyikan cichlid Neolamprologus meeli were observed in their natural habitat. The home ranges of males and females overlapped with each other. Most groups included one to six young. Paternal and maternal relationships were determined for 22 young from DNA microsatellite markers. Three types of kinship were found: (I) kinship to both the male and female; (II) kinship to females only; and (III) nonkinship to both sexes. In the groups with type II young, step-fathering or sneaking may have occurred. Type III young were larger than type I, suggesting that the former were of sufficient size to leave their birth nest and settle in the territories of foster parents. Both males and females drove out potential predators of young (including three species of Lepidiolamprologus) as a parental behavior. Adults with type III young attacked approaching predators with as much frequency as those with type I young only, indicating that they provided alloparental care. Adults and young swam together, but, a significant difference existed in the frequencies of interactions between adults versus kin young and adults versus non-kin young. The results suggest that both adults and young recognized kin.
  • Y Hayakawa, R Akiyama, H Munehara, A Komaru
    ENVIRONMENTAL BIOLOGY OF FISHES 65 (3) 311 - 317 0378-1909 2002/11 [Refereed][Not invited]
     
    We used an artificial semen emission test to examine the semen transporting role of parasperm (unflagellated sperm), which are produced along with eusperm ( normal sperm) by an incomplete meiosis in the marine sculpin Hemilepidotus gilberti. After separation of contents of semen ( eusperm, parasperm, and seminal plasma) by centrifugation, the distance traveled by semen discharged vertically from a syringe into seawater was compared among various test semen; eusperm semen ( eusperm re-mixed with seminal plasma), parasperm semen ( parasperm re-mixed with seminal plasma), normal semen ( eusperm and parasperm re-mixed with seminal plasma), and natural semen (unmodified semen). Parasperm semen traveled more than 1.5 times as far as the eusperm semen. The lateral dispersion width of normal semen after emission was significantly narrower than that of eusperm semen. These findings indicate that parasperm can reduce the lateral dispersion and prolong the distance semen travels. The eusperm ratio in the lower portion of the emitted semen did not differ from that in the upper portion, indicating that eusperm evenly distribute within the ejaculate and reach the lower portion of semen. Since males cannot closely approach eggs that are deposited in the narrow space between the female's belly and the spawning substrate, restraint of lateral dispersion and prolongation of the distance semen traveled would increase the number of eusperm arriving at eggs, despite reduction of eusperm in the ejaculate.
  • Y Hayakawa, A Komaru, H Munehara
    JOURNAL OF MORPHOLOGY 253 (3) 243 - 254 0362-2525 2002/09 [Refereed][Not invited]
     
    The developmental process of eu- and paraspermatozoa in the cottid fish, Hemilepidotus gilberti, was observed by electron microscopy. Euspermatozoa of H. gilberti consist of a thin disk-like sperm head (about 3 mum in length), a short middle piece, and a long flagellum, but lack an acrosome. On the other hand, during spermiogenesis, aberrant spermatids, rich in cytoplasm and possessing binuclei, develop into cysts containing spermatids. The developing aberrant spermatids connect with normal spermatids and euspermatozoa by intercellular bridges. The early phase of chromatin condensation in aberrant spermatids is almost identical to that in normal spermatids, but the nuclei in the later phase develop into a mass of highly electron-dense globules. Since the aberrant spermatids complete karyokinesis but not cytokinesis at telophase of the second meiotic division, they are considered to develop into hyperpyrenic cells due to incomplete cytokinesis of the second meiotic division. These spermatids are oval in shape (5-7 mum in diameter) and lack a flagellum. The aberrant spermatids of H. gilberti are shed along with euspermatozoa and amount to about 50% of semen in volume. Judging from their form and developmental process, aberrant spermatids produced in H. gilberti are considered hyperpyrenic paraspermatozoa. (C) 2002 Wiley-Liss, Inc.
  • Y Hayakawa, H Munehara
    ICHTHYOLOGICAL RESEARCH 49 (3) 291 - 293 1341-8998 2002/08 [Refereed][Not invited]
     
    The initiation of sperm motility in a noncopulatory marine cottid fish, Gymnocanthus herzensteini, was examined. The spermatozoa, which were immotile in seminal plasma, initiated motility at osmolalities of more than 500 mOsm kg(-1) in NaCl solution and 400 mOsm kg(-1) in KCl and mannitol solutions, indicating that the initiation of sperm motility depends on changes in external osmolality, in contrast with that of the sperm of other marine cottid fish, which are motile in seminal plasma. This study revealed that there are plural manner of initiation of sperm motility in marine cottid fish, which are oviparous but include both copulatory and noncopulatory modes.
  • Y Hayakawa, H Munehara, A Komaru
    ENVIRONMENTAL BIOLOGY OF FISHES 64 (4) 419 - 427 0378-1909 2002/08 [Refereed][Not invited]
     
    Synopsis In many species of animals, males normally produce parasperm (dimorphic sperm) along with eusperm (normal sperm) during spermatogenesis. In the present study, to clarify the role of parasperm of the non-copulatory sculpin Hemilepidotus gilberti, whose reproduction is characterized by polyandrous oviposition involving sneaking by neighboring territorial males, we observed the movements of parasperm. Parasperm could not move by themselves, but they were transported in solutions by passive movement due to collisions with actively swimming eusperm. In the viscous ovarian fluid (OF), which isolates eggs from seawater by covering them during spawning, parasperm did not exhibit any movement. However, they could be transported by eusperm movement in solutions with dissolved OF, partly because the viscosity of the fluid become lower. And then, in some solutions parasperm formed lumps. Lump formation of parasperm was also observed at the boundary surface of an egg mass where OF contacted seawater. Eusperm added experimentally to a solution in which parasperm were forming lumps were engulfed in the lumps and never escaped. Thus, Jump formation of parasperm would be obstacles for the later arriving eusperm. Although lumps formed against both kin and non-kin eusperm, parasperm are thought to be available to overcome sperm competition which would occur during spawning that involves sneaking being almost concurrent with lump formation. The territorial male eusperm reach the eggs while his parasperm hinder other males' eusperm from reaching the eggs. Thus, we concluded that parasperm of H. gilberti play a role on protection of paternity by blocking rival eusperm physically from approaching eggs.
  • H Munehara, VG Sideleva, A Goto
    JOURNAL OF FISH BIOLOGY 60 (4) 981 - 988 0022-1112 2002/04 [Refereed][Not invited]
     
    In an examination of the distribution of nesting spaces of two Baikal sculpins, Paracottus kneri and Cottus kessleri, along two transects offshore at Bolshye Koty, a total of 43 P. kneri nests, 32 C kessleri nests and one Batrachocottus baicalensis nest was found. Males of these species established breeding nests under overhanging stones in the same manner as most freshwater sculpins, but nests of each species were clearly partitioned in separate zones. Cottus kessleri nests were found where the lake floor was mostly covered with overhanging stones. Paracottus kneri nests, however, were found where the lake floor was moderately covered with overhanging stones. Two mixed-species brooding nests with a C kessleri guarding male were found in an area bounded by the two zones. Each of these nests comprised one P. kneri egg mass and several C kessleri egg masses, guarded by a C kessleri male. The nest distribution of these fishes appears to reflect intra- and interspecific competition for overhanging stones as a reproductive resource rather than interspecific difference of nest selection. (C) 2002 The Fisheries Society of the British Isles, Published by Elsevier Science Ltd. All rights reserved.
  • H Munehara, N Nagai, Y Narimatsu
    MOLECULAR ECOLOGY NOTES 2 (1) 70 - 71 1471-8278 2002/03 [Refereed][Not invited]
     
    Hypoptychus dybowskii (Gasterosteiformes) exhibits allopaternal care frequently caused by various types of male reproductive tactics (sneaking, egg desertion and taking over). In order to understand this interesting reproductive system, we isolated microsatellites loci from H. dybowskii. Five microsatellites showed 2-10 alleles and expected heterozygosities ranged from 0.15 to 0.84. These were not significant deviations from Hardy-Weinberg expectations. These results suggest that these novel polymorphic loci should be useful for parentage analysis of H. dybowskii.
  • Y Koya, H Munehara, K Takano
    JOURNAL OF EXPERIMENTAL ZOOLOGY 292 (2) 145 - 155 0022-104X 2002/02 [Refereed][Not invited]
     
    Elkhorn sculpin, Alcichthys, alcicornis, is a marine teleost with a unique reproductive mode called "internal gametic association," in which sperm introduced into the ovary by copulation enter the micropylar canal of ovulated eggs in the ovarian cavity, but actual sperm-egg fusion does not occur until the eggs have been released into sea water. It is also known that this fish is a multiple spawner, which spawns at intervals of a few days for one month, and the sperm introduced into the ovary at the beginning of the spawning season retain their fertilizability for the entire period. To clarify how the fertilizability of sperm is maintained internally, the ultrastructure of sperm, the morphological characteristics related to sperm storage in the ovary, and the characteristics of sperm motility were investigated. Mature sperm generally have the normal form of teleost sperm, devoid of acrosomal structures. However, it was found that the midpiece is comparatively elongated and has a compact aggregation of many small-size mitochondria. The intraovarian sperm remained floating in the ovarian fluid throughout the spawning season. The sperm showed high motility in isotonic and weak alkaline solution, containing sodium ions, which was similar to the ovarian fluid of this fish. Sperm continued to move in artificial ovarian fluid for 7-14 days. Considering these results together, it is thought that the intraovarian sperm move throughout the spawning season due to the plentiful energy generated by the many mitochondria. (C) 2002 Wiley-Liss, Inc.
  • J Nagao, H Munehara
    CRABS IN COLD WATER REGIONS: BIOLOGY, MANAGEMENT, AND ECONOMICS 19 323 - 337 2002 [Not refereed][Not invited]
     
    To clarify the annual reproductive cycle of the helmet crab, Telmessus cheiragonus, in the coastal regions of Usujiri, southern Hokkaido, Japan, the gonads of a total of 266 adult crabs (148 males and 118 females) were examined histologically. Ovarian maturity was divided into five stages (stages 1-5). The ovaries were immature (stage 1 or stage 2) during October-March and maturing during April-September. The females became ovigerous during October-January. In males, the developmental stage of the testicular lobules was divided into six stages (stages I-VI). All stages were observed throughout the year but immature lobules (stages I-IV) occurred most frequently in May-June. The mating season was estimated to between March and July with a peak of mating activity in May. This information was based on the occurrence of soft-shell females. From a result of these observations, the annual reproductive cycle of this species is estimated to require a year and was divided into the ovarian maturation phase (April-September) and the incubation phase (October-March). During the ovarian maturation phase, the molting of the females and subsequent mating seemed to occur frequently. During the incubation phase, most females maintained immature ovaries. Inhibition of ovarian maturing during the incubation phase may be a characteristic of the reproductive cycle of this species.
  • Kentaro Nozaki, Hiroshi Morino, Hiroyuki Munehara, Valentina G. Sideleva, Katsuki Nakai, Mitsugu Yamauchi, Olga M. Kozhova, Masami Nakanishi
    Limnology 3 (3) 175 - 180 1439-8621 2002 [Not refereed][Not invited]
     
    The composition, biomass, and photosynthetic activity of benthic algal communities were investigated in a littoral zone of the south basin of Lake Baikal in July 1998. A transect survey revealed a vertical transition of the dominant taxonomic groups: Ulothrix and diatoms dominated in the shallowest station (depth, 0.5m), whereas only diatoms were found in a station with a depth of 1 m. In deeper stations (depth, 2-3m), an endemic filamentous green alga, Draparnaldioides baicalensis, was the predominant form, but in addition to this species, Tetraspora and diatoms were also abundant in algal communities collected in the deepest stations (depth, 5-6m). Biomass expressed as chlorophyll a (Chl a) varied in the range of 8 mg Chl a·m-2 (at a depth of 1m) and 300 mg Chl a·m-2 (at a depth of 3m). The maximum photosynthetic rate (of carbon, C) of the community dominated by Ulothrix was 0.24 mg C·mg Ch1 a 1·h 1, whereas the corresponding rate of the community dominated by Draparnaldioides was 1.51 mg C· Ch1 a 1·h1.
  • Munehara, H, S. Awata, R. Katoh, M. Kohda, T. Sunobe
    Bull. Fish. Sci. Hokkaido Univ 北海道大学 52 (3) 131 - 133 1346-1842 2001 [Not refereed][Not invited]
  • Y Hayakawa, H Munehara
    JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY 256 (1) 51 - 58 0022-0981 2001/01 [Not refereed][Not invited]
     
    Fertilized residual eggs were observed in the ovaries of spent females of a non-copulatory sculpin Hemilepidotus gilberti Jordan and Starks. Fertilized eggs were present in 23 of 35 females, and approximately 38% of the total residual eggs (n = 227) were fertilized. These eggs were thought to be fertilized facultatively with spermatozoa that entered the ovary through ovarian fluid during spawning. The high calcium concentration (1.42+/-0.21 mM kg(-1)) in ovarian fluid, which is beyond the threshold concentration required for fertilization, may anew internal fertilization to occur. Embryos at various developmental stages were observed, but all were deformed and surrounded by unhardened chorions. Since no larvae were observed, all the fertilized residual eggs would have degenerated in the ovary in accordance with other unfertilized residual eggs. These observations suggest that the ovary of the oviparous fish H. gilberti is an unsuitable environment for embryos to develop, possibly because it may be unable to supply developing embryos with needed elements, such as oxygen. (C) 2001 Elsevier Science B.V. All rights reserved.
  • Y Narimatsu, H Munehara
    BEHAVIOUR 138 85 - 96 0005-7959 2001/01 [Not refereed][Not invited]
     
    The territoriality of parental males and the hatching late of egg masses in their territories were examined in Hypoptychus dybowskii, a species in which territorial males care for egg masses only just after mating, and sneaker males are known to occur. Most males deserted the territories with egg masses, but the hatching rates of abandoned and attended egg masses were similar. A large percentage of the deserted territories with egg masses were taken over by non-territorial males. Comparison of the mating success between males that deserted territories and those that attended territories showed that territory desertion occurred when males experienced fewer chances to mate. These results indicate that territorial males contributed little to embryonic survivorship after egg mass hardening, and deserted their territories depending on the mating rate. Such an unique reproductive strategy may be adaptive when there are no parental costs after arrangement of egg masses, high hatching rates of abandoned egg masses, and a high chance of sneaking.
  • 細野隆史, 宗原弘幸
    北大水産科学研究彙報 北海道大学 52 (1) 11 - 37 1346-1842 2001 [Not refereed][Not invited]
     
    ハイマツの冬胞子葉さび病菌Coleosporium pini-pumilaeは,ハイマツの針葉に形成される冬胞子世代のみを有する短世代種と考えられていたが,その証明はなく,さらに精子器形成の有無,感染後の潜伏期間などは不明であった.岩手山の網張国有林で採取した冬胞子から形成された担子胞子によるストローブマツおよびアカマツ新葉への接種試験の結果,10カ月後にストローブマツのみ冬胞子が形成された.以上の結果,本種には精子器は存在せず,冬胞子世代のみをもつ短世代種であることが実験的に証明された.本実験では,被接種植物を平地の苗畑(盛岡市)に置いたため潜伏期間は10カ月であったが,自然発生地での観察から,潜伏期間は2年にわたる場合も多いと考察した.
  • H Munehara, Z Kanamoto, T Miura
    ICHTHYOLOGICAL RESEARCH 47 (3) 287 - 292 1341-8998 2000/08 [Not refereed][Not invited]
     
    The spawning behavior of Hexagrammos otakii, H. octogrammus and H. agrammus was observed in two different regions of northern Japan using underwater video cameras placed near nests guarded by males. The spawning behavior of the three species consisted of similar patterns, although body size and nuptial coloration and nest location of territorial male H. otakii differed from those of the other two Hexagrammos species. The courtship display of territorial males in each species involved rushing, butting and undulation of the trunk. When a female entered the nest, the male leaned his head on the future spawning bed in the nest and spasmodically undulated his trunk. The female that responded to the courtship laid her eggs within the seaweed bed. The territorial male then passed over the eggs, touching his genital pore to the egg mass, and released sperm. Sneaking by other males was frequently observed following the sperm emission. In both regions, females of H. octogrammus and H. agrammus commonly responded to courtship of male H. otakii and mated with them, but not vice versa. Possible reasons for the natural occurrence of such unidirectional hybridization are discussed.
  • H Munehara, O Takenaka
    JOURNAL OF ETHOLOGY 18 (2) 101 - 104 0289-0771 2000 [Not refereed][Not invited]
     
    The fertilization success of sneaking behavior in a paternal care fish, Hexagrammos otakii, was estimated using microsatellites as genetic markers. Sneaking behavior was observed using a video camera placed near the nest of a breeding territorial male. Two egg masses fertilized by different patterns of sperm Emission by the territorial male and sneaker males were examined for paternity discrimination. When a sneaker emitted a large amount of sperm after sperm emission by the territorial male, the sneaker fertilized more eggs than the territorial male. When the territorial male and a sneaker alternately emitted semen, the territorial male fertilized the most eggs. These results suggest that both the amount of emitted sperm and the timing of sperm emission are important factors in sperm competition.
  • Y Narimatsu, H Munehara
    CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES 56 (10) 1849 - 1855 0706-652X 1999/10 [Not refereed][Not invited]
     
    The effects of spawn date on survival and growth during the embryonic, larval, and juvenile stages of a coastal fish, Hypoptychus dybowskii (Gasterosteiformes), were examined. Monitoring of embryos using SCUBA showed that the embryonic period decreased as the season progressed and the hatching rate was lowest for the early-spawn cohort (EC). Analysis of otolith daily growth increments indicated that EC larvae had much lower survival and growth rates than larvae of middle-spawn (MC) and late-spawn cohorts (LC), but there were no large differences in either rate among juveniles of the three cohorts. EC suffered the highest mortality rates in the embryonic and larval stages; these high rates were linked with slow development and growth, probably caused by below-optimum water temperatures. EC fish grew over a longer period and reached larger body size than MC and LC fish. These results suggest that intraannual variations in growth pattern and survival rate in the embryonic and larval stages were caused by spawn date differences, which favored the LC in the study year, but the EC might have a size-dependent advantage in survivorship and reproductive success during the postjuvenile stages.
  • J Nagao, H Munehara, K Shimazaki
    JOURNAL OF CRUSTACEAN BIOLOGY 19 (1) 77 - 83 0278-0372 1999/02 [Not refereed][Not invited]
     
    External morphological changes in embryos of the hair crab Erimacrus isenbeckii (Brandt) reared in the laboratory were observed. Embryonic development was divided into 9 stages based on morphological changes: precleavage stage, cleavage and blastula stage, gastrula stage, naupliar stage, metanaupliar stage, pigmented-eye stage, heartbeat-initiation stage, prezoea stage, and prehatching stage. Embryos spawned by a female in January developed to the gastrula stage by March. Embryos from another female developed from the gastrula stage to the prehatching stage from March to December, and hatched in January. These results suggest that the incubation period under laboratory conditions was about 12 months. Since one female collected in February still carried prezoea-stage embryos, the embryonic growth rate in the laboratory was expected to be higher than in the field. It is thought that the length of the incubation period is affected by many environmental factors, but the embryonic growth rate is mainly controlled by water temperature. Thus, around Hukkaido, where specimens studied were collected, incubating females may be distributed in temperatures cooler than in the laboratory.
  • クチバシカジカの繁殖生態
    宗原弘幸, 佐藤長明, 渡辺信次
    伊豆海洋通信 10 2 - 3 1999 [Not refereed][Not invited]
  • Y Hayakawa, H Munehara
    ENVIRONMENTAL BIOLOGY OF FISHES 52 (1-3) 181 - 186 0378-1909 1998/06 [Refereed][Not invited]
     
    To clarify the extracellular environment for external fertilization in the non-copulating marine sculpin Hemilepidotus gilberti, sperm motility was measured in NaCl, KCl, mannitol solutions, seawater, and ovarian fluid. Spermatozoa of H. gilberti actively moved in seminal plasma the moment they were removed from the genital papilla. Spermatozoa showed higher motility in NaCl solution at osmolalities between 300-400 mOsmol kg(-1). In KCI and in mannitol solutions, spermatozoa actively moved at osmolalities between 500 and 800 mOsmol kg(-1), and at osmolality 300 mOsmol kg(-1), respectively. The ovarian fluid was a transparent and viscous gelatinous material, rich in sodium with an osmolality of 340 mOsmol kg(-1). Sperm motility in the ovarian fluid lasted more than 90 min, which was six times longer than in seawater. This sperm motility under conditions isotonic to body fluid is similar to that of copulating marine sculpins rather than to other non-copulating marine fishes. In addition, eggs of H. gilberti could be fertilized in the ovarian fluid. This suggests that external fertilization takes place under physiological conditions similar to the internal conditions of the ovary provided by the ovarian fluid, which isolates the eggs from sea water for several hours after spawning. This manner of fertilization is thought to be one of the evolutionary pre-adaptations allowing copulation among marine sculpins.
  • HJ Liu, Y Sakurai, H Munehara, K Shimazaki
    FISHERIES SCIENCE 63 (5) 655 - 658 0919-9268 1997/10 [Refereed][Not invited]
     
    The diel rhythms of oxygen consumption and activity level were measured over a 24-hr period in three size groups of starved juvenile flounder Paralichthys olivaceus by continuous-flow respiratory and video-observation analysis, respectively. In the small group (mean body weight +/- SD, MBW: 3.3 +/- 0.9 g), two peaks of oxygen consumption were observed at 03:00 and 17:00 hours, and the hourly metabolic rates were not significantly different between dark and light periods. In the medium group (MBW: 20.3 +/- 3.7 g) and the large group (MBW: 58.5 +/- 7.1 g), only a single peak was observed at 04:00 or 06:00 hours, and the hourly consumption rates were significantly higher in the dark than in the light. For all groups, the highest oxygen consumption rates occurred under conditions of weak light or darkness. The routine metabolic rate is described by the equation logM=0.643 log W -0.387, where M is the oxygen consumption rate (mgO(2)/kg/hr) and W is body weight (kg) at 20 degrees C. The diel pattern in activity rate (duration of swimming per hour in minutes) was similar to the pattern of oxygen consumption; fishes were more active during the night (mean activity rate = 5.0 min/hr) than during the day (mean activity rate = 2.2 min/hr). The relation between rate of oxygen consumption and activity rate is discussed.
  • RA Khan, H Munehara, K Ryan, JW Lawson
    CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE 75 (8) 1280 - 1284 0008-4301 1997/08 [Not refereed][Not invited]
     
    A study was conducted to determine the prevalence and effects of two species of blood-feeding copepods on their definitive fish hosts, viz. Haemobaphes cyclopterina parasitizing Arctic cod (Boreogadus saida) and H. intermedius infecting tidepool sculpins (Oligocottus maculosus). Infected and uninfected Arctic cod and tidepool sculpins were captured by SCUBA and dip net in the northwest Atlantic and northeast Pacific, respectively. Biological variables such as condition factor, hepatic somatic index, gonadal somatic index, and haematocrit were compared between the two groups of Arctic cod of both sexes, whereas only condition factor was compared in the two groups of sculpins of both sexes. Prevalence of H. cyclopterina (8%) was considerably lower than that of H. intermedius (46%). This difference is probably associated with the hosts' behaviour, as the Arctic cod is pelagic whereas the tidepool sculpin is restricted to the littoral zone, where infections are probably acquired. Infected Arctic cod of both sexes had significantly lower condition factor, hepatic and gonadal somatic indices, and haematocrit than non-parasitized fish. Only females harboured Large numbers of the parasite and showed even more dramatic changes than the corresponding groups. The growth period of H. cyclopterina on Arctic cod from the time of infection to the fully developed egg sac stage is probably about 6 months. In tidepool sculpins, condition factor was significantly lower in infected than in uninfected fish. These results, especially for the Arctic cod, parallel those reported for gadoid fish following infection with haematophagous species of Lernaeocera that impair growth and reproduction.
  • Y Narimatsu, H Munehara
    FISHERIES SCIENCE 63 (4) 503 - 508 0919-9268 1997/08 [Not refereed][Not invited]
     
    Age and daily growth of Hypoptychus dybowskii collected periodically off Usujiri, southern Hokkaido, June 1993 to June 1994, were investigated using otolith-increment counts. Daily increment formation was verified by comparing the number of increments formed after alizarin complexone marking with the number of days after treatment. Most growth occurs during the first 6 months from hatching. The relationship between standard length and the number of daily growth increments was best fitted to a Logistic curve for male, and a Gompertz curve for females: (males) Lt=56.25/(1+exp(-0.034(t-68.00))) and (females) Lt=63.16exp(-exp-0.018(t-54.98)) No specimen had more than 365 increments in its sagittae, suggesting this species has a life span of one year.
  • Y Koya, H Munehara, K Takano
    JOURNAL OF MORPHOLOGY 233 (2) 153 - 163 0362-2525 1997/08 [Not refereed][Not invited]
     
    The morphology of female sperm storage during the spawning period and the morphology of sperm degradation after the spawning period were investigated by electron microscopy in a copulating teleost, Alcichthys alcicornis. The spermatozoa were maintained in the ovarian cavity, floating in the ovarian fluid during the spawning period. The spermatozoa then degenerated and were phagocytized by macrophages invading the ovarian cavity after the spawning period. In the ovary during the spawning period, horseradish peroxidase used as a tracer revealed tight junctional complexes connecting adjacent cells of the inner ovarian epithelia (ovarian wall epithelium and ovigerous lamella epithelium). This indicates that a compartmentalization of the ovarian cavity occurs during the spawning period. The junctional complexes were breached after the spawning period, as shown by the fact that horseradish peroxidase penetrated the ovarian cavity via the intercellular space between the adjoining ovigerous lamella epithelia. These results suggest that the spermatozoa in the ovarian cavity are isolated from the maternal immune system by the tight junctional complexes between the adjoining inner ovarian epithelia during the spawning period, and then are eliminated by immune cells following the breakdown of the junctional complexes after the spawning period. (C) 1997 Wiley-Liss, Inc.
  • H Munehara, Y Koya, Y Hayakawa, K Takano
    JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY 211 (2) 279 - 289 0022-0981 1997/04 [Not refereed][Not invited]
     
    Conditions for the initiation of fertilization and the initial fertilization process were investigated using histological observations of eggs of Hemitripterus villosus (Pallas), an oviparous fish that undergoes internal insemination. Eggs obtained from ovaries of inseminated females already had spermatozoa present inside the micropylar canal, but showed no signs of fertilization. The contents of the cortical alveolae were discharged after the eggs were immersed in seawater, suggesting that fertilization is initiated after spawning. These observations indicate that the spawning mode of H. villosus is one of internal gametic association with external fertilization, as previously reported in Alcichthys alcicornis and Blepsias cirrhosus. Fertilization occurred in an isotonic media rich in calcium ions. Calcium ion concentration of the ovarian fluid of H. villosus was lower than that of the media in which fertilization occurred. These results suggest the failure to initiate fertilization internally was caused by a deficiency of calcium ions in the ovarian fluid. The plug-like structure in the outer opening of the micropylar canal appeared 10 min after the eggs' immersion in seawater. The plug-like structure appears to originate from irregular particles dispersed on the vestibule. Another plug-like structure appeared in the inner opening of the micropylar canal 2 h after the eggs' immersion in seawater. Rather than blocking polyspermy, the two plug-like structure probably prevent foreign micro-organisms from invading the ooplasm during the long embryonic period (4 months). (C) 1997 Elsevier Science B.V.
  • The reproductive biology and early life stages of Podothecus sachi (Pisces: Agonidae)
    Munehara, H
    Fish. Bull 95 612 - 619 1997 [Not refereed][Not invited]
  • アイナメにおけるマイクロサテライトDNA多型を利用した父子判定
    宗原弘幸
    DNA多型 5 218 - 222 1997 [Not refereed][Not invited]
  • Development of artificial reefs for the hoursehair crab.
    Munehara, H, J. Nagao, T. Maruyama
    The 13th Int. Symp. Biol. Crabs, Alaska Sea Grant College Program 613 - 625 1996 [Not refereed][Not invited]
  • Nagao, J, H. Munehara, K. Shimazaki
    The 13th Int. Symp. Biol. Crabs, Alaska Sea Grant College Program 315 - 331 1996 [Not refereed][Not invited]
  • Hayakawa, Y, Munehara, H
    Icthyol. Res 43 (1) 73 - 78 1996 [Not refereed][Not invited]
  • H Munehara, T Miura
    JOURNAL OF ETHOLOGY 13 (2) 191 - 193 0289-0771 1995/12 [Not refereed][Not invited]
  • H MUNEHARA, Y KOYA, K TAKANO
    JOURNAL OF FISH BIOLOGY 45 (6) 1105 - 1111 0022-1112 1994/12 [Not refereed][Not invited]
     
    The reason for failure to initiate fertilization internally was examined in a cottid fish, the elkhorn sculpin, Alcichthys alcicornis which has internal gametic association and external fertilization. While eggs could be activated in calcium free hypertonic media but not be Fertilized, fertilization occurred in isotonic media rich in calcium ions. The rate of fertilization was dependent on calcium concentration, and eggs were not fertilized in solutions with a calcium ion concentration of less than 0.57 mmol kg(-1). Calcium ions could be replaced to some extent by magnesium ions, but the former were the more effective in fertilization. Since calcium ion concentration of ovarian fluid of A. alcicornis was 0.41 mmol kg(-1), it was inferred that low calcium concentration in the ovarian fluid was the cause of the failure of A. alcicornis eggs to fertilize internally.
  • H MUNEHARA, A TAKENAKA, O TAKENAKA
    JOURNAL OF ETHOLOGY 12 (2) 115 - 120 0289-0771 1994/12 [Not refereed][Not invited]
     
    The elkhorn sculpin Alcichthys alcicornis spawns and subsequently copulates, and the eggs are then cared for by the male. DNA fingerprinting was used to determine the paternity of males for the clutches guarded by them. When a female was mated with 4 males in succession in aquaria, males did not fertilize the eggs spawned just before copulation unless the female was unimpregnated but fathered the eggs spawned by the female later. In the field, near the end of the breeding season, males were genetically unrelated to the clutches in their territories. We concluded that males guard non-kin eggs for the opportunity to copulate and to fertilize the future clutches of their mates.
  • Y KOYA, H MUNEHARA, K TAKANO, H TAKAHASHI
    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-PHYSIOLOGY 106 (1) 25 - 29 0300-9629 1993/09 [Not refereed][Not invited]
     
    1. The motility of spermatozoa in several marine sculpins, which exhibit a special reproductive manner of the internal gametic association, was measured in various artificial solutions, ovarian fluid and seminal plasma. 2. In the elkhorn sculpin, Alcichthys alcicornis, spermatozoa showed high motility in solutions of 300 to 400 mOsm/kg, containing sodium ion, with pH higher than 7.5, which coincided with the nature of ovarian fluid of the fish. 3. Spermatozoa of sunrise sculpin, Pseudoblennius cottoides, and elegant sculpin, Bero elegans, were motile at osmolalities isotonic to the ovarian fluid but not at osmolalities higher than 500 and 800 mOsm/kg, respectively, indicating that the gametic association in these fish is carried out exclusively in their ovaries. 4. Spermatozoa of littledragon sculpin, Blepsias cirrhosus, were motile at osmolalities higher than 300 mOsm/kg, but not in sea water, suggesting an internal gametic association to occur in this species of sculpins. 5. The results indicate that spermatozoa of the marine sculpins with the internal gametic association show their motility in environmental conditions appropriate to respective reproductive modes.
  • H MUNEHARA
    ENVIRONMENTAL BIOLOGY OF FISHES 33 (4) 395 - 398 0378-1909 1992/04 [Not refereed][Not invited]
     
    The sea raven, Hemitripterus villosus, deposits its eggs on polychaete tubes (Salmacina sp.) in the coastal waters of Usujiri, southern Hokkaido, Japan. This is contradictory to investigations in the Bay of Peter the Great, Soviet Union, where eggs are deposited in narrow clefts. The egg masses are found among the bunchy worm tubes or between the base of the colony and the substrate. The spawning habit of H. villosus is distinct from 'spawner in live invertebrates' such as the little dragon sculpin Blepsias cirrhosus, which specifically associates with a sponge. That of H. villosus is classified as a 'cavity spawner'.
  • H MUNEHARA
    JAPANESE JOURNAL OF ICHTHYOLOGY 38 (2) 179 - 184 0021-5090 1991/10 [Not refereed][Not invited]
     
    It was established that the little dragon sculpin Blepsias cirrhosus uses the sponge species Mycale adhaerens as a spawning bed. The eggs were completely concealed in the sponge tissues, and caused the sponge skeleton to be partly damaged. It is conceivable that the exclusive utilization of M. adhaerens by B. cirrhosus is a consequence of the advantageous softness and thickness of the sponge which allows the fish to inject the eggs. The eggs deposited in the sponge seemed to take advantage of predator avoidance, a constant supply of oxygen, and little interference by bacteria.
  • H MUNEHARA, K SHIMAZAKI
    JAPANESE JOURNAL OF ICHTHYOLOGY 38 (1) 31 - 34 0021-5090 1991/06 [Not refereed][Not invited]
     
    This paper describes both embryonic development and newly hatched larval morphology of the little dragon sculpin Blepsias cirrhosus. The eggs of B. cirrhosus are almost spherical, 3.0-3.2 mm in diameter, and have a yolk color of burnt orange. Development is very slow, being especially sluggish once the embryo appears. The embryo begins forming from the 10th day. In size, the early embryo is less than 1/6 of the yolk's circumference. Incubation at 10-degrees-C takes about 200 days, 50 days shorter than the incubation period in a natural environment, with a mean water temperature of 11-degrees-C. The notochord length of newly-hatched larvae averages 11.1 mm. The larvae are developed so fully that the notochord is already flexing and the caudal and pectoral rays are forming.
  • H MUNEHARA, K TAKANO, Y KOYA
    JAPANESE JOURNAL OF ICHTHYOLOGY 37 (4) 391 - 394 0021-5090 1991/02 [Not refereed][Not invited]
     
    In the copulating cottid species, Blepsias cirrhosus, the point at which fertilization occurred was determined experimentally. Ovulated eggs were obtained directly from the ovary of impregnated females. Eggs maintained in ovarian fluid did not show any signs of development, whereas most of the eggs which had been placed in seawater had developed to the 4-cell stage after 24 hrs. The eggs kept in ovarian fluid initiated segmentation when later transferred into seawater. Histological examination showed that a number of spermatozoa had entered the micropyle, but that penetration did not occur in eggs that were not immersed in seawater. In these eggs, the metaphase spindle of the second meiotic division was observed in the ooplasm, at the animal pole. These results indicate that, in impregnated females, the spermatozoa associate with the eggs in the ovarian cavity, but that fertilization occurs externally when the eggs are spawned.
  • H MUNEHARA, H OKAMOTO, K SHIMAZAKI
    JOURNAL OF ETHOLOGY 8 (1) 21 - 24 0289-0771 1990/06 [Not refereed][Not invited]
  • H MUNEHARA, K TAKANO, Y KOYA
    COPEIA 1989 (3) 673 - 678 0045-8511 1989/08 [Not refereed][Not invited]
  • H MUNEHARA, K SHIMAZAKI
    NIPPON SUISAN GAKKAISHI 55 (3) 423 - 429 0021-5392 1989/03 [Not refereed][Not invited]
  • H MUNEHARA
    JAPANESE JOURNAL OF ICHTHYOLOGY 35 (3) 358 - 364 0021-5090 1988/12 [Not refereed][Not invited]
  • Munehara, H, Shimazaki, K, Mishima, S
    Bull. Fac. Fish., Hokkaido Univ 38 (1) 27 - 33 1987 [Not refereed][Not invited]
  • 宗原弘幸, 三島清吉
    魚類学雑誌 日本魚類学会 33 (1) 46 - 50 0021-5090 1986 [Refereed][Not invited]

Books etc

MISC

  • Azuma Taisei, Munehara Hiroyuki  北海道大学水産科学研究彙報  71-  (2)  51  -67  2021/12/23  [Not refereed]
     
    We conducted SCUBA-based surveys of the larval and juvenile fish fauna in reef and seaweed areas in the inshore region of Usujiri, Hakodate, along the Pacific coast of southern Hokkaido, Japan, from 2019 to 2020. A total of 100 species in 10 orders and 44 families were identified based on morphological observations and DNA barcoding analyses of the cytochrome c oxidase subunit I (COI) gene. Of these species, two specimens of the labrid, Pseudolabrus sieboldi Mabuchi and Nakabo, 1997, one specimen of the cottid, Cottus hangiongensis Mori, 1930, two specimens of the blennid, Petroscirtes breviceps (Valenciennes, 1836), and one specimen of the gobiid, Pterogobius zacalles Jordan and Snyder, 1901, represent the first records of these four species in the study area. In addition, three specimens of the Stichaeid, Lumpenopsis pavlenkoi Soldatov, 1916, represent the first records captured during juvenile stages of this species, and one specimen of the pleuronectid, Lepidopsetta mochigarei (Snyder, 1911) represent the first juvenile captured in Usujiri of these species. The fish list is also added in this report.
  • 宗原 弘幸  NIPPON SUISAN GAKKAISHI  87-  (1)  57  -57  2021/01/15  [Not refereed]
  • 安房田智司, 五十嵐直, 瓜生知史, 古屋康則, 宗原弘幸  日本生態学会大会講演要旨(Web)  66th-  2019
  • MATSUBARA Naoto, MATSUDA Yuta, AKAMATSU Tomonari, TAKAHASHI Ryuzo, MUNEHARA Hiroyuki, YASUMA Hiroki  J. Marine Acoust. Soc. Jpn.  45-  (2)  37  -46  2018  [Not refereed][Not invited]
     
    <p>We observed the sound production and properties of fox jacopever (<i>Sebastes vulpes</i>) in a water tank experiment to obtain basic information for the Passive Acoustic Monitoring (PAM). Six pairs of experiments including mature and immature fishes were conducted, and sound properties with and without agonistic behavior were compared. Fox jacopever produced low frequency pulses under 2,000 Hz. Pulse number ranged between 1–77, pulse duration was 0.005–0.220 s, pulse period was 0.001–0.989 s, and peak frequency was 258–490 Hz. These properties were changed by the presence or absence of agonistic behavior. Higher peak frequency over 400 Hz was observed only when a pair included an immature fish. Our results showed the potential use of fish sounds for estimating size and status of territorial behavior in this species by PAM.</p>
  • 伊藤岳, 守田昌哉, 柴小菊, 稲葉一男, 宗原弘幸, 山崎彩, 古屋康則, 武島弘彦, 安房田智司  日本生態学会大会講演要旨(Web)  65th-  ROMBUNNO.P2‐128 (WEB ONLY)  2018  [Not refereed][Not invited]
  • 百田 和幸, 宗原 弘幸  Memoires of the Faculty of Fisheries Sciences, Hokkaido University  59-  (1)  1  -17  2017/12  [Not refereed][Not invited]
     
    We conducted SCUBA-based surveys of the larval and juvenile fish fauna in reef and seaweed areas in the inshore region of Usujiri, Hakodate, along the Pacific coast of southern Hokkaido, Japan, from 2011 to 2015. A total of 97 species in 9 orders and 33 families were identified based on morphological observations and DNA barcoding analyses of the Cytochrome c oxidase subunit I(COI) gene. Of these species, three specimens of the syngnathid, Urocampus nanus Gunther, 1870, three specimens of the pomacentrid, Chromis notata(Temminck and Schlegel, 1843), one specimen of the pomacentrid, Abudefduf notatus(Day, 1870), one specimen of the pomacentrid, Pomacentrus coelestis Jordan and Starks, 1901, one specimen of the tetrarogid, Hypodytes rubripinnis(Temminck and Schlegel, 1845), 20 specimens of the labrid, Halichoeres tenuispinis(Gunther, 1862), 20 specimens of the labrid, Parajulis poecileptera(Temmminck and Schlegel, 1843), one specimen of the cottid, Pseudoblennius sp. 2 and one specimen of the ostraciid Ostracion cubicus Linnaeus, 1758, represent the first records of these nine species in the study area. Of these nine species, the records for U.nanus, A.nonatus, H.rubripinnis, H.tenuispinis, P.sp.2 and O.cubicus represent the northernmost records of these six species in the Pacific Ocean.
  • 東村拓志, 矢部衞, 宗原弘幸  日本魚類学会年会講演要旨  50th-  47  2017/09/14  [Not refereed][Not invited]
  • 山崎彩, 津田栄, 河田雅圭, 宗原弘幸  日本魚類学会年会講演要旨  50th-  148  2017/09/14  [Not refereed][Not invited]
  • 富樫孝司, 山崎彩, 安房田智司, 古屋康則, 阿部拓三, 鶴岡理, 武島弘彦, MALKEVICH Alexander, 宗原弘幸  日本魚類学会年会講演要旨  50th-  143  2017/09/14  [Not refereed][Not invited]
  • 吉田隼佑, 鈴木将太, 宗原弘幸  日本魚類学会年会講演要旨  50th-  59  2017/09/14  [Not refereed][Not invited]
  • 宗原弘幸  日本魚類学会年会講演要旨  50th-  142  2017/09/14  [Not refereed][Not invited]
  • 鈴木将太, 三宅翔太, 荒井克俊, 藤本貴史, 宗原弘幸  日本魚類学会年会講演要旨  50th-  141  2017/09/14  [Not refereed][Not invited]
  • 橋爪伸崇, 宗原弘幸  日本魚類学会年会講演要旨  50th-  31  2017/09/14  [Not refereed][Not invited]
  • 荻野瑛乃, 鈴木将太, 大友洋平, 宗原弘幸  日本水産学会大会講演要旨集  2017-  10  2017/03/26  [Not refereed][Not invited]
  • 鈴木将太, 宗原弘幸  日本水産学会大会講演要旨集  2017-  73  2017/03/26  [Not refereed][Not invited]
  • 百田和幸, 百田和幸, 百田和幸, 宗原弘幸  北海道大学水産科学研究い報  67-  (1)  7‐12  -12  2017/03/15  [Not refereed][Not invited]
     
    Aspects of the reproductive ecology and early life history of the tubenose poacher Pallasina barbata(Steindachner,1876) were clarified based on observations on the development of eggs without artificial insemination and on morphological changes of larvae and juveniles. The reproductive mode was identified as internal gametic association, which has been reported in several cottoids. The inferred spawning periods and hatching periods were May and March, respectively, suggesting the embryonic period lasted 10 months, which is near the longest known among the Agonids. The eggs were found in the sponge Mycale adhaerens. Newly-hatched larvae were in the flexion stage, and the notochord length(NL) was 7.3mm. In the flexion larvae stage, two white spots occurred in the dorsal finfold, which have not been reported in larvae of other Agonids. Extension of the snout and protrusion of the lower jaw barbel began from 11.7mm NL at post-flexion. At 20.2mm standard length(SL), the finfold had disappeared, and all the fin ray number attained the fixed number. The scale number of bony plates reached the same number as in the adult at 28.7mm SL.
  • 宗原弘幸, 鈴木将太, 橋爪伸崇, 加藤大棋, 吉田隼祐, 大河内裕典, 東村拓志  日本水産学会北海道支部大会講演要旨集  2017-  13  2017  [Not refereed][Not invited]
  • Xuchun Qiu, Suzanne Lydia Undap, Masato Honda, Toshio Sekiguchi, Nobuo Suzuki, Yohei Shimasaki, Hironori Ando, Waka Sato-Okoshi, Toshihiro Wada, Tomoki Sunobe, Satoshi Takeda, Hiroyuki Munehara, Hisashi Yokoyama, Noriyuki Momoshima, Yuji Oshima  Journal of Radioanalytical and Nuclear Chemistry  311-  (1)  121  -126  2017/01/01  [Not refereed][Not invited]
     
    © 2016, Akadémiai Kiadó, Budapest, Hungary. Radionuclide concentrations in wharf roaches inhabiting coastal areas of Honshu, Japan, were investigated in October 2011 and June 2012. Relative high concentrations of 110mAg (2.1–127 Bq kg-wet−1), 134Cs (2.6–61 Bq kg-wet−1), and 137Cs (3.5–92 Bq kg-wet−1) were detected in specimens from the eastern Honshu areas. Significantly lower 137Cs concentrations (0.7–1.6 Bq kg-wet−1) were detected in specimens from western and northern Honshu. The decay-corrected 137Cs concentration was significantly inversely correlated with the distance from the Fukushima Dai-ichi Nuclear Power Plant. Thus, wharf roach may serve as a good bioindicator for monitoring radioactive contamination of its habitats.
  • 五十嵐直, 瓜生知史, 古屋康則, 宗原弘幸, 安房田智司  日本魚類学会年会講演要旨  49th-  97  2016/09/22  [Not refereed][Not invited]
  • 大友洋平, 阿部拓三, 宗原弘幸  日本魚類学会年会講演要旨  49th-  47  2016/09/22  [Not refereed][Not invited]
  • 安房田智司, 佐々木晴香, 後藤智仁, 古屋康則, 武島弘彦, 山崎彩, 宗原弘幸  日本魚類学会年会講演要旨  49th-  33  2016/09/22  [Not refereed][Not invited]
  • 宗原弘幸, 鈴木将太, 三宅翔太, 堀田海帆, 川口幹子  日本魚類学会年会講演要旨  49th-  99  2016/09/22  [Not refereed][Not invited]
  • 伊藤岳, 守田昌哉, 柴小菊, 稲葉一男, 宗原弘幸, 山崎彩, 古屋康則, 武島弘彦, 安房田智司  日本魚類学会年会講演要旨  49th-  96  2016/09/22  [Not refereed][Not invited]
  • 松原直人, 松田裕太, 高橋竜三, 赤松友成, 宗原弘幸, 木村暢夫, 前川和義, 安間洋樹  日本水産工学会学術講演会講演論文集  2016-  133‐134  -134  2016/04/29  [Not refereed][Not invited]
  • 富樫孝司, 山崎彩, 安房田智司, 古屋康則, 阿部拓三, 鶴岡理, 武島弘彦, マルケビッチ アレックス, 宗原弘幸  日本水産学会大会講演要旨集  2016-  47  2016/03/26  [Not refereed][Not invited]
  • 百田和幸, 宗原弘幸  日本水産学会大会講演要旨集  2016-  47  2016/03/26  [Not refereed][Not invited]
  • 萩原聖士, 須山喜市, 東典子, 堤尚信, 西尾朋高, 市村政樹, 三坂尚行, 鈴木渉太, 宮城大助, 古市明文, 市川卓, 松原創, 川崎琢真, 宗原弘幸, 高橋英祐, 山羽悦郎, 井尻成保, 足立伸次  日本水産学会大会講演要旨集  2016-  16  2016/03/26  [Not refereed][Not invited]
  • 三宅翔太, 鈴木将太, 荒井克俊, 宗原弘幸  日本水産学会大会講演要旨集  2016-  78  2016/03/26  [Not refereed][Not invited]
  • 山崎 彩, 永野 優季, 菊地 優, 百田 和幸, 鈴木 将太, 五十嵐 健志, 宗原 弘幸  Memoirs of the Faculty of Fisheries Sciences, Hokkaido University  57-  (1)  1  -24  2015/12  [Not refereed][Not invited]
     
    From 2012 to 2014 intertidal and coastal fishes were collected while SCUBA diving at Ohata, Kawauchi, Asizaki and Wakinosawa in the Shimokita Peninsula, Aomori Prefecture, northern Japan. During these surveys, 21 families, 43 genera and 51 species were collected and 7 families 7 genera and 7 species were photographed. Eleven species(Halichoeres tenuispinis, Porocottus allisi, Furcina osimae, Furcina ishikawae, Pseudoblennius cottoides, Lethotremus awae, Aptocyclus ventricosus, Chirolophis saitone, Neoclinus briyope, Parablennius yatabei, and Sagamia geneionema) were newly recorded from Ohata, 3 from kawauchi(Omobranchus elegans, Repomucenus valenciennei, and Acentrogobius virgatulus), and 1 from Ashizaki(Acentrogobius virgatulus), although they have been previously recorded from other areas of Aomori Prefecture.
  • 古屋康則, 三橋直哉, 安房田智司, 伊藤岳, 伊藤岳, 宗原弘幸  魚類学雑誌  62-  (2)  121  -131  2015/11/05  [Not refereed][Not invited]
     
    Abstract Artificial fertilization experiments were performed and male and female gonads observed histologically to confirm the oldest known description (published 1934) of the reproductive mode for internal gamete association (IGA) in Vellitor centropomus (Cottidae). Stripped eggs from mature females were unfertilized such commencing after their immersion in seawater, indicating that V. centropomus is an IGA species. Many spermatozoa were stored in the immature ovary with non-vitellogenic oocytes, evidence that males of the species mature before females and that copulation occurs when females are still immature. The male reproductive organ consisted of paired testes, a specialized seminal vesicle and a functional urogenital papilla. A sperm duct in the testicular hilus was absent. Spermatogenesis occurred sequentially, posterior most first, suggesting that it occurs over an extended period of time. A ventral luminal ampulla, central expanded main sperm duct and dorsal saccular ampulla were observed in the seminal vesicle, all parts being involved in sperm storage. The saccular ampulla had an exocrine function, secreting a periodic acid–Schiff (PAS)-positive substance. Sperm heads stored in the posterior part of the testis or lumen of the seminal vesicle were also PAS-positive. Sperm heads were slender, a typical morphology in IGA species.
  • 松原直人, 宗原弘幸, 高橋竜三, 木村暢夫, 前川和義, 安間洋樹  日本水産学会大会講演要旨集  2015-  4  2015/09/22  [Not refereed][Not invited]
  • 野原健司, 佐久間啓, 安房田智司, 宗原弘幸, 矢部衛, 坂井恵一, 作田純輝, 岩田陽介, 佐久間恵介, 松野太亮, 峯岸岳弘  日本魚類学会年会講演要旨  48th-  58  2015/08/28  [Not refereed][Not invited]
  • 山崎彩, 津田栄, 西宮佳志, 宗原弘幸  日本進化学会大会プログラム・講演要旨集(Web)  17th-  ROMBUNNO.P‐73 (WEB ONLY)  2015/08/20  [Not refereed][Not invited]
  • M. Hatano, T. Abe, T. Wada, H. Munehara  JOURNAL OF FISH BIOLOGY  86-  (3)  1121  -1128  2015/03  [Not refereed][Not invited]
     
    Cyclopterids were hatched from egg batches that were laid in two empty buccinid snail shells collected from a depth of 340 m in the Sea of Japan. Larvae were reared to identify species and to describe the morphological changes associated with metamorphosis. The fin rays of all fins were mostly complete and the pelvic fins were modified to form suckers, or adhesive discs, at the time of hatching. Juveniles immediately attached themselves to the bottom and there was no planktonic stage. The body surface was smooth with no spines or bony tubercles. At 4 months after hatching, the fine spines present on the head and trunk of juveniles transformed into bony tubercles. At 7 months after hatching, fishes became sexually dimorphic including the position and development patterns of bony tubercles. Importantly, these sexually dimorphic changes in morphology corresponded closely with descriptions of different species. Specifically, females could be classified as Eumicrotremus asperrimus, and young and fully developed males as Cyclopteropsis bergi and Cyclopteropsis lindbergi, respectively. These observations resolved a previously ambiguous hypothesis regarding the taxonomy of these cyclopterid taxa. Cyclopteropsis bergi and C. lindbergi may be synonyms of E. asperrimus. (C) 2015 The Fisheries Society of the British Isles
  • 松永啓志, UNDAP Suzanne Lydia, 本田匡人, 関口俊男, 鈴木信雄, 安東宏徳, 大越和加, 須之部友基, 武田哲, 宗原弘幸, 島崎洋平, 大嶋雄治  九州大学大学院農学研究院学芸雑誌  70-  (1)  21  -25  2015/02/27  [Not refereed][Not invited]
     
    本研究ではPFOSをフナムシへ曝露してその蓄積性を検討した. その結果, フナムシへPFOSが蓄積し, 生物学的半減期は11.9日と推定された. さらに日本沿岸の14地点から採取したフナムシへのPFOSの体内濃度の測定を行った結果, 港湾2地点の各1個体からのみPFOSが検出された. よって渚域におけるPFOSの汚染の程度は低いと推測された. 今後, PFOSが検出された地点での分析個体数を増やし, 渚域におけるPFOSの環境汚染をより明確にする必要がある.In an exposure test, wharf roach (Ligia exotica Roux) was exposed to perfluorooctane sulfonate (PFOS )via diet (0.1 mg/g-diet) for 2 days. 1 day after cessation of exposure, concentration of PFOS was increased to 1019 ± 144 ng/g-wet and still detected to 377 ± 321 ng/g-wet at 12 days after the exposure. Biological half-life of PFOS in wharf roach was estimated to be 11.9 days. In a field study, wharf roach were collected from 14 coastal sites in Japan. PFOS were detected from each one individual in Tsuyazaki, Fukuoka Pref. (215 ng/g-dry) and Taira, Nagasaki Pref. (601 ng/g-dry). These results suggested that wharf roach could be a promised biomonitoring species for PFOS in coastal area.
  • Koya Yasunori, Mitsuhashi Naoya, Awata Satoshi, Ito Takeshi, Munehara Hiroyuki  Jpn. J. Ichthyol.  62-  (2)  121  -131  2015  [Not refereed][Not invited]
     
    <p><b>Abstract </b>Artificial fertilization experiments were performed and male and female gonads observed histologically to confirm the oldest known description (published 1934) of the reproductive mode for internal gamete association (IGA) in <i>Vellitor centropomus</i> (Cottidae). Stripped eggs from mature females were unfertilized such commencing after their immersion in seawater, indicating that <i>V. centropomus</i> is an IGA species. Many spermatozoa were stored in the immature ovary with non-vitellogenic oocytes, evidence that males of the species mature before females and that copulation occurs when females are still immature. The male reproductive organ consisted of paired testes, a specialized seminal vesicle and a functional urogenital papilla. A sperm duct in the testicular hilus was absent. Spermatogenesis occurred sequentially, posterior most first, suggesting that it occurs over an extended period of time. A ventral luminal ampulla, central expanded main sperm duct and dorsal saccular ampulla were observed in the seminal vesicle, all parts being involved in sperm storage. The saccular ampulla had an exocrine function, secreting a periodic acid–Schiff (PAS)-positive substance. Sperm heads stored in the posterior part of the testis or lumen of the seminal vesicle were also PAS-positive. Sperm heads were slender, a typical morphology in IGA species.</p>
  • 宗原弘幸, 堀田海帆, 三宅翔太, 鈴木将太  日本水産学会北海道支部大会講演要旨集  2015-  24  2015  [Not refereed][Not invited]
  • 大友洋平, 阿部拓三, 宗原弘幸  日本水産学会北海道支部大会講演要旨集  2015-  23  2015  [Not refereed][Not invited]
  • 安房田智司, 佐々木晴香, 後藤智仁, 古屋康則, 武島弘彦, 山崎彩, 宗原弘幸  日本水産学会北海道支部大会講演要旨集  2015-  22  2015  [Not refereed][Not invited]
  • 山崎彩, 中野翼, 宗原弘幸  日本水産学会北海道支部大会講演要旨集  2015-  21  2015  [Not refereed][Not invited]
  • Aya Yamazaki, Hiroyuki Munehara  ICHTHYOLOGICAL RESEARCH  62-  (2)  240  -243  2015/01  [Not refereed][Not invited]
     
    Gymnocanthus herzensteini and Gymnocanthus intermedius (Cottidae) larvae are common in northern Japan, but can be difficult to distinguish. In this study, morphological observations and mitochondrial DNA analyses were conducted to determine if melanophore patterns could be used to distinguish the two species. The morphological observations identified two groups with distinct melanophore patterns. Subsequent molecular analyses determined with high bootstrap values that the group with numerous body melanophores was G. intermedius, and the group with fewer melanophores was G. herzensteini. These results indicate that melanophore distribution patterns in larvae are useful for identifying G. intermedius and G. herzensteini.
  • 古屋康則, 三橋直哉, 安房田智司, 宗原弘幸  日本魚類学会年会講演要旨  47th-  20  2014/11/14  [Not refereed][Not invited]
  • 河相吉紀, 古屋康則, 安房田智司, 宗原弘幸  日本魚類学会年会講演要旨  47th-  20  2014/11/14  [Not refereed][Not invited]
  • 安房田智司, 後藤智仁, 古屋康則, 武島弘彦, 山崎彩, 宗原弘幸  日本魚類学会年会講演要旨  47th-  21  2014/11/14  [Not refereed][Not invited]
  • 荒谷美咲, 宗原弘幸  日本魚類学会年会講演要旨  47th-  74  2014/11/14  [Not refereed][Not invited]
  • 山崎彩, 花田祐一, 津田栄, 宗原弘幸  日本魚類学会年会講演要旨  47th-  74  2014/11/14  [Not refereed][Not invited]
  • M. R. Kimura-Kawaguchi, M. Horita, S. Abe, K. Arai, M. Kawata, H. Munehara  JOURNAL OF FISH BIOLOGY  85-  (2)  189  -209  2014/08  [Not refereed][Not invited]
     
    a Natural hybrids between the boreal species Hexagrammos octogrammus and two temperate species Hexagrammos agrammus and Hexagrammos otakii were observed frequently in southern Hokkaido, Japan. Previous studies revealed that H. octogrammus is a maternal ancestor of both hybrids; the hybrids are all fertile females and they frequently breed with paternal species. Although such rampant hybridization occurs, species boundaries have been maintained in the hybrid zone. Possible explanations for the absence of introgressions, despite the frequent backcrossing, might include clonal reproduction: parthenogenesis, gynogenesis and hybridogenesis. The natural hybrids produced haploid eggs that contained only the H. octogrammus genome (maternal ancestor) with discarded paternal genome and generated F-1-hybrid type offspring by fertilization with the haploid sperm of H. agrammus or H. otakii (paternal ancestor). This reproductive mode was found in an artificial backcross hybrid between the natural hybrid and a male of the paternal ancestor. These findings indicate that the natural hybrids adopt hybridogenesis with high possibility and produce successive generations through hybridogenesis by backcrossing with the paternal ancestor. These hybrids of Hexagrammos represent the first hybridogenetic system found from marine fishes that widely inhabit the North Pacific Ocean. In contrast with other hybridogenetic systems, these Hexagrammos hybrids coexist with all three ancestral species in the hybrid zone. The coexistence mechanism is also discussed. (C) 2014 The Fisheries Society of the British Isles
  • 鈴木将太, 荒井克俊, 宗原弘幸  日本水産学会大会講演要旨集  2014-  67  2014/03/27  [Not refereed][Not invited]
  • 入江雄一朗, 鈴木将太, 三宅翔太, 宗原弘幸  日本水産学会大会講演要旨集  2014-  159  2014/03/27  [Not refereed][Not invited]
  • 宗原弘幸, 入江雄一朗, 鈴木将太, 三宅翔太  日本水産学会大会講演要旨集  2014-  75  2014/03/27  [Not refereed][Not invited]
  • 羽多野桃子, 阿部拓三, 和田年史, 宗原弘幸  日本水産学会大会講演要旨集  2014-  99  2014/03/27  [Not refereed][Not invited]
  • 大嶋雄治, 本田匡人, 松永啓志, 島崎洋平, 小山次朗, 伊藤一輝, 堀就英, 宗原弘幸, 武田哲, 大越和加, 安東宏徳, 鈴木信雄, 関口俊男, 須之部友基  日本水産学会大会講演要旨集  2014-  145  2014/03/27  [Not refereed][Not invited]
  • 風間香澄, 宗原弘幸  日本水産学会大会講演要旨集  2014-  203  2014/03/27  [Not refereed][Not invited]
  • 山崎彩, 李昂, MARKEVICH A, 宗原弘幸  日本水産学会大会講演要旨集  2014-  99  2014/03/27  [Not refereed][Not invited]
  • 安房田智司, 後藤智仁, 古屋康則, 武島弘彦, 山崎彩, 宗原弘幸  日本動物行動学会大会発表要旨集  33rd-  73  2014  [Not refereed][Not invited]
  • 大吉徹, 宗原弘幸  日本水産学会北海道支部大会講演要旨集  2014-  32  2014  [Not refereed][Not invited]
  • 鈴木将太, 荒井克俊, 宗原弘幸  日本水産学会北海道支部大会講演要旨集  2014-  33  2014  [Not refereed][Not invited]
  • 宗原弘幸, 堀田海帆, 三宅翔太, 鈴木将太  日本水産学会北海道支部大会講演要旨集  2014-  34  2014  [Not refereed][Not invited]
  • 百田和幸, 大島由貴, 宗原弘幸  日本水産学会北海道支部大会講演要旨集  2014-  31  2014  [Not refereed][Not invited]
  • 松原直人, 宗原弘幸, 赤松友成, 木村暢夫, 前川和義, 安間洋樹  日本水産学会北海道支部大会講演要旨集  2014-  21  2014  [Not refereed][Not invited]
  • 入江雄一朗, 鈴木将太, 宗原弘幸  日本水産学会大会講演要旨集  2013-  73  2013/09/19  [Not refereed][Not invited]
  • MUNEHARA HIROYUKI  NSUGAF  79-  (5)  905  -905  2013/09/15  [Not refereed][Not invited]
  • ARAI KATSUTOSHI, KOMARU AKIRA, MUNEHARA HIROYUKI  NSUGAF  79-  (5)  900  2013/09/15  [Not refereed][Not invited]
  • 鈴木将太, 荒井克俊, 宗原弘幸  日本水産学会大会講演要旨集  2013-  202  2013/03/26  [Not refereed][Not invited]
  • 宗原弘幸  日本水産学会大会講演要旨集  2013-  288  2013/03/26  [Not refereed][Not invited]
  • 大嶋雄治, UNDAP Suzanne, 本田匡人, 松永啓志, 島崎洋平, 宗原弘幸, 武田哲, 大越和加, 安東宏徳, 鈴木信雄, 関口俊男, 須之部友基  日本水産学会大会講演要旨集  2013-  165  2013/03/26  [Not refereed][Not invited]
  • YAMAZAKI Aya, MUNEHARA Hiroyuki  日本生態学会大会講演要旨集  60th-  197  2013/03/05  [Not refereed][Not invited]
  • ARAI KATSUTOSHI, KOMARU AKIRA, MUNEHARA HIROYUKI  NIPPON SUISAN GAKKAISHI  79-  (5)  900  -900  2013  [Not refereed]
  • Katsutoshi Arai, Akira Komaru, Hiroyuki Munehara  Nippon Suisan Gakkaishi (Japanese Edition)  79-  (5)  900  2013  [Not refereed][Not invited]
  • Hiroyuki Munehara  Nippon Suisan Gakkaishi (Japanese Edition)  79-  (5)  905  2013  [Not refereed][Not invited]
  • 宗原弘幸, 堀田海帆, 鈴木将太, 入江雄一朗  日本水産学会大会講演要旨集  2012-  147  2012/03/26  [Not refereed][Not invited]
  • 宗原弘幸  日本魚類学会年会講演要旨  45th-  95  2012  [Not refereed][Not invited]
  • 山崎彩, 宗原弘幸  日本魚類学会年会講演要旨  45th-  55  2012  [Not refereed][Not invited]
  • 堀田海帆, 鈴木将太, 風間香澄, 木村幹子, 宗原弘幸  日本魚類学会年会講演要旨  45th-  67  2012  [Not refereed][Not invited]
  • Noriko Azuma, Yuta Seki, Yoshiaki Kikkawa, Tomoyuki Nakagawa, Yoko Iwata, Taku Sato, Hiroyuki Munehara, Susumu Chiba  CONSERVATION GENETICS RESOURCES  3-  (3)  529  -531  2011/07  [Not refereed][Not invited]
     
    We have developed and characterized 13 novel polymorphic microsatellite markers for the Hokkai Shrimp, Pandalus latirostris, to provide an effective tool for conducting genetic studies on this species. No linkage disequilibria and no deviation from HWE were detected in these markers. In 32 individuals from Lake Notoro in Hokkaido, Japan, the number of alleles and expected heterozygosities ranged from 7 to 22 and from 0.84 to 0.95, respectively, suggesting the availability of these markers for ecological studies and conservation genetics in this species.
  • 宗原弘幸, 五十嵐理人, 植松孝昌, 堀田海帆  日本水産学会大会講演要旨集  2011-  67  2011/03/27  [Not refereed][Not invited]
  • 五十嵐理人, 植松孝昌, 堀田海帆, 木村幹子, 宗原弘幸  日本水産学会大会講演要旨集  2011-  67  2011/03/27  [Not refereed][Not invited]
  • カジカ類における異型精子の分化機構と機能
    早川洋一, 中内祐二, 小林牧人, 宗原弘幸, 鬼武一夫, 渡辺明彦  カジカ類の世界 ~適応と進化~  133  -143  2011  [Refereed][Invited]
  • 成田英毅, 赤川泉, 宗原弘幸  日本魚類学会年会講演要旨  44th-  47  2011  [Not refereed][Not invited]
  • 五十嵐理人, 堀田海帆, 植松孝昌, 宗原弘幸  日本魚類学会年会講演要旨  44th-  27  2011  [Not refereed][Not invited]
  • 堀田海帆, 木村幹子, 宗原弘幸  日本魚類学会年会講演要旨  44th-  28  2011  [Not refereed][Not invited]
  • 山崎彩, MARKEVICH Alexander, 山村織生, 宗原弘幸  日本魚類学会年会講演要旨  44th-  70  2011  [Not refereed][Not invited]
  • 堀田海帆, 入江雄一郎, 宗原弘幸  日本水産学会北海道支部大会講演要旨集  2011-  25  2011  [Not refereed][Not invited]
  • Sato Noriyosi, Sekizawa Ayami, Awata Satoshi, Munehara Hiroyuki, Nakashima Yasuhiro  Venus  69-  (3)  214  -217  2011  [Not refereed][Not invited]
     
    同時的雌雄同体であるサラサウミウシにおいて8遺伝子座のマイクロサテライトマーカーを開発した。これらのマーカーでは,一遺伝子座あたりの対立遺伝子数は1から30,平均が15と高い多型性が認められた。多型性を示す7遺伝子座のマーカーヘテロ接合度の実測値と予測値は,それぞれ0.409から0.905,0.518から0.960の範囲であった。以上,サラサウミウシの親子判定に使用可能と考えられる多様性の高いマイクロサテライトマーカーを特定した。
  • 佐藤成祥, 宗原弘幸  ちりぼたん  40-  (3/4)  138  -144  2010/10/31  [Not refereed][Not invited]
  • 永尾次郎, 宗原弘幸  日本ベントス学会・日本プランクトン学会合同大会講演要旨集  2010(CD-ROM)-  ROMBUNNO.131  2010/10/08  [Not refereed][Not invited]
  • Hiroyuki Munehara, Hiroshi Murahana  ENVIRONMENTAL BIOLOGY OF FISHES  88-  (4)  323  -331  2010/08  [Not refereed][Not invited]
     
    The sperm allocation pattern of a copulating marine cottid fish, Alcichthys alcicornis, was investigated. A total of 86 mating events using six males were conducted in aquarium tanks over 10 days, and in 36 of them, spermatozoa were collected using a false copulation method. Males released 3-8 x 10(8) spermatozoa in early events, with the number decreasing gradually during subsequent mating events. This sperm allocation was represented as an "early investment and tapering" pattern. It was discussed why males have significantly higher sperm release in early spawning events. The reproductive behavior consists of spawning and subsequent copulation. Spermatozoa have the ability to fertilize eggs from multiple clutches, and in earlier produced clutches the level of sperm competition should be relatively low. In addition, if early spawn happens to be the first spawn with a female, spermatozoa that are released into the water column after spawning are responsible for fertilizing the female's first clutch. The probability of this occurring should decrease dramatically as the season progresses, due to the highly synchronous seasonal spawning of females. All of these factors should select for high sperm numbers in early ejaculates. Based on such reproductive ecology of A. alcicornis we hypothesize that this sperm allocation pattern is an adaptive reproductive strategy in response to egg availability and sperm competition occurring within the ovarian cavity.
  • 木村 幹子, 宗原 弘幸  Kaiyo monthly  42-  (6)  337  -345  2010/06  [Not refereed][Not invited]
  • 木村幹子, 宗原弘幸  月刊海洋  42-  (6)  337  -345  2010/06/01  [Not refereed][Not invited]
  • 木村幹子, CROW‐SANCHEZ Karen, 宗原弘幸  日本水産学会大会講演要旨集  2010-  77  2010/03/26  [Not refereed][Not invited]
  • 佐藤成祥, 春日井隆, 宗原弘幸  日本生態学会大会講演要旨集  57th-  396  2010/03/15  [Not refereed][Not invited]
  • 木村幹子, 河田雅圭, 阿部周一, 荒井克俊, 宗原弘幸  日本生態学会大会講演要旨集  57th-  249  2010/03/15  [Not refereed][Not invited]
  • 古屋康則, 早川洋一, 阿部拓三, MARKEVICH Alexander, 矢部衞, 宗原弘幸  日本魚類学会年会講演要旨  43rd-  39  2010  [Not refereed][Not invited]
  • 横山良太, SIDELEVA Valentina G, 高橋洋, 宗原弘幸, 木下泉, 後藤晃  日本魚類学会年会講演要旨  43rd-  24  2010  [Not refereed][Not invited]
  • 堀田海帆, 木村幹子, 宗原弘幸  日本魚類学会年会講演要旨  43rd-  63  2010  [Not refereed][Not invited]
  • 堀田海帆, 木村幹子, 宗原弘幸  日本水産学会北海道支部大会講演要旨集  2010-  31  2010  [Not refereed][Not invited]
  • 宗原弘幸, 五十嵐理人, 植松孝昌, 堀田海帆  日本水産学会北海道支部大会講演要旨集  2010-  30  2010  [Not refereed][Not invited]
  • 田中善規, 鶴岡理, 二村智之, 宗原弘幸  北海道大学水産科学研究い報  59-  (3)  73  -80  2009/12/08  [Not refereed][Not invited]
     
    One specimen of syngnathid, Hippocampus mohnikei (Bleeker, 1853), eight specimens of callionymid, Repomucenus curvicornis (Valenciennes, 1837), two specimens of callionymid, Repomucenus valenciennei (Temminck and Schlegel, 1843), 12 specimens of paralichthyid, Tarphops oligolepis (Bleeker, 1858), and 17 specimens of monacanthid, Rudarius ercodes (Jordan and Fowler, 1902) were collected from inshore Usujiri, the Pacific coast of southern Hokkaido, Japan. These specimens of H. mohnikei, R. valenciennei, T. oligolepis, and R. ercodes represent the northernmost records of these species in the Pacific Ocean, and these of R. curvicornis represent the first records of these species from the study area.
  • 田中 善規, 鶴岡 理, 二村 智之, 宗原 弘幸  Bulletin of fisheries sciences, Hokkaido University  59-  (3)  73  -80  2009/12  [Not refereed][Not invited]
     
    One specimen of syngnathid, Hippocampus mohnikei (Bleeker, 1853), eight specimens of callionymid, Repomucenus curvicornis (Valenciennes, 1837), two specimens of callionymid, Repomucenus valenciennei (Temminck and Schlegel, 1843), 12 specimens of paralichthyid, Tarphops oligolepis (Bleeker, 1858), and 17 specimens of monacanthid, Rudarius ercodes (Jordan and Fowler, 1902) were collected from inshore Usujiri, the Pacific coast of southern Hokkaido, Japan. These specimens of H. mohnikei, R. valenciennei, T. oligolepis, and R. ercodes represent the northernmost records of these species in the Pacific Ocean, and these of R. curvicornis represent the first records of these species from the study area.
  • 宗原弘幸  海洋水産エンジニアリング  9-  (88)  69  -73  2009/11/10  [Not refereed][Not invited]
  • 宗原 弘幸  海洋水産エンジニアリング  9-  (88)  69  -73  2009/11  [Not refereed][Not invited]
  • 谷川友里, 田原大輔, 宗原弘幸, 早川洋一, 古屋康則  日本水産学会大会講演要旨集  2009-  41  2009/03/27  [Not refereed][Not invited]
  • 安房田智司, 木村幹子, 佐藤成祥, 坂井慶太, 宗原弘幸, 阿部拓三  日本水産学会大会講演要旨集  2009-  235  2009/03/27  [Not refereed][Not invited]
  • 宗原弘幸, 木村幹子  日本水産学会大会講演要旨集  2009-  226  2009/03/27  [Not refereed][Not invited]
  • 鶴岡理, 山中智之, 阿部拓三, 武藤文人, 宗原弘幸, 矢部衞, 仲谷一宏  北海道大学水産科学研究い報  58-  (3)  43  -50  2009/02/28  [Not refereed][Not invited]
     
    A holocentrid Ostichthys japonicus (Cuvier, 1829), a platycephalid Platycephalus sp., a cottid Icelus sekii Tsuruoka, Munehara and Yabe, 2006, an agonid Bothragonus occidentalis Lindberg, 1935, and a stichaeid Lumpenopsis pavlenkoi Soldatov, 1916 were collected from off Usujiri, Hakodate, Hokkaido, northern Japan, the western North Pacific. Ostichthys japonicus was previously recorded from the south of Aomori Prefecture and further southern waters; thus present report represents the northern-most record of the species. Platycephalus sp. and B. occidentalis were known only by pelagic juveniles from off Usujiri. Hence, we report the first records of adults of these species from this waters. As I. sekii was previously known only from its type locality, off Rausu and Urakawa, Hokkaido, present report is the second and the southern-most records of this species. Lumpenopsis pavlenkoi has been collected from Peter the Great Bay, Okhotsk coast of Hokkaido and the waters around the Kamchatka Islands, thus present report represents southern-most record of this species in the Pacific Ocean.
  • 古屋康則, 早川洋一, 宗原弘幸  日本魚類学会年会講演要旨  42nd-  69  2009  [Not refereed][Not invited]
  • 木村幹子, 阿部周一, 荒井克俊, 河田雅圭, 宗原弘幸  日本魚類学会年会講演要旨  42nd-  68  2009  [Not refereed][Not invited]
  • 阿部拓三, 山中智之, 宗原弘幸  日本魚類学会年会講演要旨  42nd-  33  2009  [Not refereed][Not invited]
  • 幸田正典, 牧野良美, HEG Dik, 武山智博, 柴田淳也, 渡辺勝敏, 堀道雄, 宗原弘幸, 安房田智司  日本魚類学会年会講演要旨  42nd-  38  2009  [Not refereed][Not invited]
  • 木村幹子, 宗原弘幸  日本魚類学会年会講演要旨  42nd-  139  -140  2009  [Not refereed][Not invited]
  • 宗原弘幸, 阿部拓三, 古屋康則, 鶴岡理  日本魚類学会年会講演要旨  42nd-  29  2009  [Not refereed][Not invited]
  • 佐藤成祥, 春日井隆, 宗原弘幸  日本動物行動学会大会発表要旨集  28th-  28  2009  [Not refereed][Not invited]
  • 古屋康則, 小池友香理, 宗原弘幸  日本動物学会大会予稿集  79th-  90  2008/08/20  [Not refereed][Not invited]
  • 早川洋一, 中内祐二, 山村織生, 宗原弘幸, 小林牧人, 渡辺明彦  日本水産学会大会講演要旨集  2008-  221  2008/03/27  [Not refereed][Not invited]
  • 中村透, 木村幹子, 宗原弘幸  日本水産学会大会講演要旨集  2008-  35  2008/03/27  [Not refereed][Not invited]
  • 八幡知基, 宗原弘幸  日本生態学会大会講演要旨集  55th-  192  2008/03/14  [Not refereed][Not invited]
  • 木村幹子, 高津哲也, 河田雅圭, 宗原弘幸  日本生態学会大会講演要旨集  55th-  360  2008/03/14  [Not refereed][Not invited]
  • 安房田智司, 太田和孝, 松本一範, 宗原弘幸, 幸田正典, 守田昌哉  日本動物行動学会大会発表要旨集  27th-  48  2008  [Not refereed][Not invited]
  • 宗原弘幸, 田中善規, 二村智之  日本魚類学会年会講演要旨  41st-  123  2008  [Not refereed][Not invited]
  • 宗原弘幸, 鶴岡理, 阿部拓三  日本水産学会大会講演要旨集  2007-  160  2007/09/25  [Not refereed][Not invited]
  • 田中善規, 宗原弘幸  日本水産学会大会講演要旨集  2007-  66  2007/03/28  [Not refereed][Not invited]
  • 宗原弘幸, 田中善規, 二村智之, 阿部真之  日本水産学会大会講演要旨集  2007-  277  2007/03/28  [Not refereed][Not invited]
  • 二村智之, 田中善規, 宗原弘幸  日本水産学会大会講演要旨集  2007-  279  2007/03/28  [Not refereed][Not invited]
  • 安河内澄子, 木村幹子, 宗原弘幸  日本水産学会大会講演要旨集  2007-  67  2007/03/28  [Not refereed][Not invited]
  • 佐藤成祥, 宗原弘幸  日本水産学会大会講演要旨集  2007-  173  2007/03/28  [Not refereed][Not invited]
  • 木村幹子, 宗原弘幸  日本生態学会大会講演要旨集  54th-  334  2007/03/19  [Not refereed][Not invited]
  • 阿部拓三, 佐藤長明, 宗原弘幸  日本魚類学会年会講演要旨  40th-  52  2007  [Not refereed][Not invited]
  • 佐藤成祥, 春日井隆, 宗原弘幸  日本動物行動学会大会発表要旨集  26th-  40  2007  [Not refereed][Not invited]
  • 宗原弘幸  日本魚類学会年会講演要旨  40th-  126  -127  2007  [Not refereed][Not invited]
  • 小池友香理, 宗原弘幸, 古屋康則  日本魚類学会年会講演要旨  40th-  51  2007  [Not refereed][Not invited]
  • 田中善規, 宗原弘幸  日本魚類学会年会講演要旨  40th-  45  2007  [Not refereed][Not invited]
  • Motoko R. Kimura, Takashi Yanagimoto, Hiroyuki Munehara  Aquatic Biology  1-  (2)  187  -194  2007  [Not refereed][Not invited]
     
    Hybridization has been frequently observed among 3 species of greenlings (genus Hexagrammos) common in waters off Japan. In order to estimate the frequency of hybridization events from egg masses collected from male territories, efficient maternal identification of numerous egg masses is required. A novel streamlined approach for maternal identification of 3 Hexagrammos spp. was developed using multiplex amplified product length polymorphism (APLP) analysis of the mitochondrial cytochrome b (Cytb) and the 12S and 16S ribosomal RNA (12-16S rRNA) regions. Concurrent use of species-specific primer sets permits the amplification of different-sized PCR products, diagnosing each species through one procedure of PCR in a single reaction tube. The APLP method produced more rapid, reliable, and cost-efficient species identifications compared to those from an established restriction fragment length polymorphism (RFLP) protocol. © Inter-Research 2007.
  • Kingo Ito, Takashi Yanagimoto, Yoko Iwata, Hiroyuki Munehara, Yasunori Sakurai  NIPPON SUISAN GAKKAISHI  72-  (5)  905  -910  2006/09  [Not refereed][Not invited]
     
    The sequence of the mitochondrial DNA noncoding region 4 (mtDNA NC4) was analyzed to investigate the genetic population structure of the spear squid Loligo bleekeri using 545 individiduals captured at six sites around Japan. MtDNA NC4 sequences of 506-528 bp were determined. A total of 55 variable nucleotide sites were detected, defining 48 haplotypes. The average haplotype diversity (0.670) and average nucleotide diversity (0.003) indicated a low level of genetic diversity in the spear squid. Analysis of molecular variation (AMOVA) indicated that most of the genetic variation was distributed within populations. The analysis of haplotype frequency distribution and F-ST values showed no significant difference among the six sampling sites. These data indicate no genetic structuring of spear squid population around Japan.
  • Kingo Ito, Takashi Yanagimoto, Yoko Iwata, Hiroyuki Munehara, Yasunori Sakurai  NIPPON SUISAN GAKKAISHI  72-  (5)  905  -910  2006/09  [Not refereed][Not invited]
     
    The sequence of the mitochondrial DNA noncoding region 4 (mtDNA NC4) was analyzed to investigate the genetic population structure of the spear squid Loligo bleekeri using 545 individiduals captured at six sites around Japan. MtDNA NC4 sequences of 506-528 bp were determined. A total of 55 variable nucleotide sites were detected, defining 48 haplotypes. The average haplotype diversity (0.670) and average nucleotide diversity (0.003) indicated a low level of genetic diversity in the spear squid. Analysis of molecular variation (AMOVA) indicated that most of the genetic variation was distributed within populations. The analysis of haplotype frequency distribution and F-ST values showed no significant difference among the six sampling sites. These data indicate no genetic structuring of spear squid population around Japan.
  • 鶴岡理, 阿部拓三, 宗原弘幸, 矢部衞  魚類学雑誌  53-  (1)  89  -93  2006/05/25  [Not refereed][Not invited]
  • 宗原 弘幸  遺伝  60-  (3)  15  -17  2006/05  [Not refereed][Not invited]
  • Osamu Tsuruoka, Takuzo Abe, Hiroyuki Munehara, Mamoru Yabe  Japanese Journal of Ichthyology  53-  (1)  89  -93  2006/05/01  [Not refereed][Not invited]
     
    Seven specimens of cottid fish, Icelinus pietschi Yabe, Soma and Amaoka, 2001, were collected from the shallow waters off Oshoro Bay and Usujiri (western Hokkaido) and Onagawa (Miyagi Pref.), Japan. This species was previously known only from the Iturup Island of southern Kuril Archipelago. The present specimens were secondly recorded to be the southernmost record for this species. In addition, colorations of fresh specimens, reproductive ecology of this species, and the intraspecific variation of the dorsal scale rows were briefly commented. © The Ichthyological Society of Japan 2006.
  • 木村幹子, 宗原弘幸  日本生態学会大会講演要旨集  53rd-  185  2006/03/24  [Not refereed][Not invited]
  • 阿部拓三, 宗原弘幸  日本動物行動学会大会発表要旨集  25th-  35  2006  [Not refereed][Not invited]
  • Youichi Hayakawa, Sonoe Furukawa, Akihiko Watanabe, Hiroyuki Munehara, Makito Kobayashi, Kazuo Onitake  ZOOLOGICAL SCIENCE  22-  (12)  1453  -1453  2005/12  [Not refereed][Not invited]
  • T Abe, H Munehara  JOURNAL OF FISH BIOLOGY  67-  (1)  201  -212  2005/07  [Not refereed][Not invited]
     
    The fertilization mode, and spawning and egg-care behaviours of the sculpin Radulinopsis taranetzi. were investigated in the laboratory. Embryonic development began only after the eggs came into contact with sea water. Females spawned c. 1000 eggs and covered them with sand using their pectoral and caudal fins. Unlike other cottids, the females guarded the egg masses after spawning. During the parental period, the supramaxillary lamina and mandibular lamina of females extended to form a disc-like structure, which was used to 'suck' water from near the surface of the egg mass. The frequency and duration of this 'sucking' behaviour increased gradually until hatching, which occurred after 23-26 days at 8 degrees C. The oxygen consumption of the embryos was positively related to the 'sucking' activity. All females in this study spawned only once during the spawning season, in contrast with the paternal-care copulating cottids, which are multiple spawners. (c) 2005 The Fisheries Society of the British Isles
  • 木村幹子, 宗原弘幸  日本水産学会大会講演要旨集  2005-  41  2005/04/01  [Not refereed][Not invited]
  • 早川洋一, 高山(渡辺, 絵理子, 渡辺明彦, 小林牧人, 宗原弘幸, 鬼武一夫  日本水産学会大会講演要旨集  2005-  50  2005/04/01  [Not refereed][Not invited]
  • 牧野良美, 武山智博, 渡辺勝敏, 宗原弘幸, 幸田正典, 安房田智司  日本生態学会大会講演要旨集  52nd-  129  2005/03/27  [Not refereed][Not invited]
  • Makino Yoshimi, Takeyama Tomohiro, Watanabe Katsutoshi, Munehara Hiroyuki, Kohda Masanori, Awata Satoshi  Abstracts of the Annual Meeting of the Ecological Society of Japan  52-  (0)  111  -111  2005  [Not refereed][Not invited]
     
    近年,メスによる子の父性操作が,昆虫や鳥類などの体内受精を行う動物で報告されている.体外受精を行う魚類では,2オスと1メスが共同繁殖を行うカワスズメ科魚類において,メスによる子の父性操作の可能性が示唆されている.しかし,その詳細は全く分かっていない.本研究では,共同繁殖を行う基質産卵型のカワスズメ科魚類<i>Julidochromis transcriptus</i>を用いて,水槽実験により,メスによる子の父性操作を検証することを試みた.野外観察から,この魚はクサビ形の巣で繁殖し,協同的一妻多夫の小オスは巣幅の狭い奥で,大オスは巣幅の広い入り口付近で放精するようである.このことから,メスは産卵する位置,つまり産卵位置の巣幅を変化させることで,メスが父性操作をしている可能性が考えられる.そこで,まずクサビ形の巣を作成し,大オス・小オス・メス(トリオ)で飼育・繁殖させて,産卵位置とそれぞれのオスの受精割合について検討したところ,巣幅の狭い位置で産卵した場合は,小オスの受精させた子どもの数が多かった.これにより,メスは産卵位置を選ぶことで父性操作が可能であると考えられる.さらに,産卵位置の巣幅が狭い場合に,小オスの保護行動の頻度が増加したことから,メスは小オスに受精させることで,小オスから保護の手伝いをより多く受けていることが示唆された.また,ペアでも同様に飼育・繁殖させると,ペア飼育で得られた卵塊はコンパクトに産まれているのに対し,トリオ飼育の卵塊は幅広く産まれていた.このことから,トリオのメスは2オスが受精できるように産卵位置や分布を操作しているようである.以上のことから,<i>J. transcriptus</i>のメスは受精を操作している可能性が高いと考えられる.
  • 宗原弘幸, 阿部拓三, 木村幹子, 佐藤長明  日本魚類学会年会講演要旨  38th-  82  2005  [Not refereed][Not invited]
  • Y Iwata, H Munehara, Y Sakurai  MARINE ECOLOGY PROGRESS SERIES  298-  219  -228  2005  [Not refereed][Not invited]
     
    The mating behavior of captive Loligo bleekeri and the paternity of the resulting progeny were examined based on behavioral observations and genetic analyses. In this species, there are 3 mating behaviors (male-parallel, head-to-head, and extra-pair), and 2 sperm storage sites in females (seminal receptacle and the opening of the oviduct), which suggest that sperm competition occurs. All 3 mating behaviors were observed, and females mated often with different males, resulting in multiple paternity within 3 of the 4 broods examined. In each brood, the male to mate last and frequently before the female spawned fertilized the most eggs (87 to 100%). A sneaker male that mated by extra-pair copulation sired 8.5% of the eggs in a brood. Some eggs were fertilized by sperm received before the start of the study, indicating that sperm can be stored for at least several days before a spawning. In the broods with multiple paternity, the paternity patterns differed among egg capsules. Male competition was more intense between similar-sized males than between different-sized males, but body size did not affect the copulative success in the male-parallel position. We found multiple mating and multiple paternity in L. bleekeri. Paternity rates differed depending on the complex of factors, mating position, timing, frequency and duration. Alternative reproductive behaviors would change these factors and lead to different paternity rates.
  • Youichi Hayakawa, Eriko Takayama-Watanabe, Akihiko Watanabe, Hiroyuki Munehara, Makito Kobayashi, Kazuo Onitake  ZOOLOGICAL SCIENCE  21-  (12)  1289  -1289  2004/12  [Not refereed][Not invited]
  • Y Hayakawa, H Munehara  JOURNAL OF FISH BIOLOGY  64-  (6)  1530  -1539  2004/06  [Not refereed][Not invited]
     
    Euspermatozoa and paraspermatozoa of a copulatory (internal insemination with external sperm transfer) cottoid fish Blepsias cirrhosus were observed ultrastructurally. Euspermatozoa of B. cirrhosus consisted of an acrosome-less, thin, disk-like sperm head (1(.)6-2(.)0 mum in length and 1(.)3-1(.)6 mum in width), a long middle piece, and a long flagellum (c. 30 mum). Aberrant spermatids, which were rich in cytoplasm and possessed two nuclei, occurred in testicular lobules. They were also observed in semen and were round (5(.)0-5(.)3 mum in diameter) and biflagellate, suggesting that they are released along with euspermatozoa at ejaculation. The nuclei of aberrant spermatids developed into masses of highly electron-dense globules. Judging from their form, nuclear condition, and connection with normal spermatids by intercellular bridges during spermiogenesis, aberrant spermatids of B. cirrhosus are considered hyperpyrenic paraspermatozoa formed by incomplete cytokinesis at the second meiotic division. (C) 2004 The Fisheries Society of the British Isles.
  • 早川洋一, 秋山良, 宗原弘幸  魚類学雑誌  51-  (1)  33  -42  2004/05/25  [Not refereed][Not invited]
  • Youichi Hayakawa, Ryo Akiyama, Hiroyuki Munehara  Japanese Journal of Ichthyology  51-  (1)  33  -42  2004/05/01  [Not refereed][Not invited]
     
    The semen of Hemilepidotus gilberti, a non-copulatory marine cottid fish, includes two sperm types; eusperm for fertilization and parasperm, which cannot be employed in fertilization. A previous study having revealed the function of parasperm as antidispersive (reducing the lateral dispersion of semen) during semen transportation, the number of eusperm arriving at an egg mass was estimated so as to confirm the significance of parasperm function. Two simple models, one including and one excluding the size effect of the egg mass at ejaculation, were used. A considerable antidispersive effect was apparent when the egg mass was small, resulting in the latter being contained within the dispersion area of semen. When male H. gilberti emit semen, eggs that hang down from the genital opening do not extend beyond the semen dispersion area. Therefore, it was concluded that parasperm in this species ensures semen transportation and promotes fertilization success in males via an antidispersive effect related to egg mass size. © The Ichthyological Society of Japan 2004.
  • 阿部拓三, 宗原弘幸  日本水産学会大会講演要旨集  2004-  55  2004/03/31  [Not refereed][Not invited]
  • 宗原弘幸, 永尾次郎, 今井洋一  日本水産学会大会講演要旨集  2004-  251  2004/03/31  [Not refereed][Not invited]
  • Kimura Motoko, Munehara Hiroyuki  Abstracts of the Annual Meeting of the Ecological Society of Japan  51-  (0)  211  -211  2004  [Not refereed][Not invited]
     
    北海道南部は、温帯性のクジメ<i>Hexagrammos agrammus</i>とアイナメ<i>H. otakii</i>、および亜寒帯性種のスジアイナメ<i>H. octogrammus</i>が同所的に生息する世界でも珍しい海域である。クジメとスジアイナメはともに浅場の藻場で繁殖するため、両種の分布が重なる海域ではしばしば雑種が報告されてきた。これに対してアイナメはクジメやスジアイナメよりも深場に生息するため、繁殖場所が隔離し交雑は回避されていると考えられてきた。しかし近年、北海道南部太平洋岸の臼尻沿岸でアイナメと他の2種との交雑が確認された。このことはこれまでアイナメと他の2種との間で働いていると考えられていた繁殖場所の違いによる交配前隔離機構が、この海域では十分に機能していないことを示している。そこで本研究では、同所的生息海域におけるアイナメ属3種の繁殖場所の分布に関する基礎的知見を得ることを目的として、臼尻沿岸における3種の繁殖場所の分布と産卵基質を調査した。<br> その結果、クジメとスジアイナメは丈が長く葉状部が枝状を呈し岩上に密生する小型藻類を、アイナメは丈が短く凹凸があり平面的に広がるコケムシ類や網などを産卵基質として利用していた。すなわちアイナメは他の2種と産卵基質の選好性が異なることが明らかとなった。3種のなわばり形成場所は産卵基質の分布に対応しており、クジメやスジアイナメは小型藻類が繁茂する浅場の岩棚部分で、アイナメはコケムシ類の付着する深場の魚礁のほか、漁港外縁にある消波ブロック帯の海底に沈む根固め用の石を入れた網袋の結び目などで見られた。また消波ブロック帯は急峻な斜面を形成するため上部には小型藻類が繁茂し、クジメやスジアイナメのなわばりも見られた。このように消波ブロック帯の複雑な地形が性質の異なる産卵基質が混在する環境を作り出し、アイナメ属の交配前隔離機構を撹乱している可能性が示唆された。<br>
  • Hayakawa Youichi, Takayama-Watanabe Eriko, Watanabe Akihiko, Munehara Hiroyuki, Kobayashi Makito, Onitake Kazuo  Zoological science  21-  (12)  1289  -1289  2004  [Not refereed][Not invited]
  • 古屋康則, 福地浩太, 宗原弘幸  日本魚類学会年会講演要旨  37th-  79  2004  [Not refereed][Not invited]
  • 古屋康則, 恩地理恵, 福地浩太, 宗原弘幸  日本水産学会中部支部大会講演要旨集  2004-  27  2004  [Not refereed][Not invited]
  • 早川洋一, 高山(渡辺, 絵理子, 渡辺明彦, 小林牧人, 宗原弘幸, 鬼武一夫  日本魚類学会年会講演要旨  37th-  55  2004  [Not refereed][Not invited]
  • 宗原弘幸  日本魚類学会年会講演要旨  37th-  127  2004  [Not refereed][Not invited]
  • J Nagao, H Munehara  FISHERIES SCIENCE  69-  (6)  1200  -1208  2003/12  [Not refereed][Not invited]
     
    To clarify the annual testicular maturation cycle in the helmet crab Telmessus cheiragonus, seasonal histological changes of the testis and occurrence of grasping pairs and recently copulated females with fresh sperm plugs were investigated. The testis was composed of seminiferous ducts with many testicular lobules. Development of the lobules was divided into six stages (spermatogonia proliferation, first spermatocyte, reduction division, spermatid, spermiogenesis and free sperm stage) based on the spermatogenic phase of the germ cells in each lobule. The mean percentage of the lobules during each stage was calculated every 1-3 months. Developed lobules occurred with a high percentage throughout the year except in June when developing lobules predominated. Grasping pairs and females with fresh sperm plugs were collected during April-July with a peak in May-June. These results suggest that the males have testis with many developing lobules in June when they are active for mating. Newly formed spermatozoa may be stored in the testis and the vas deferens until the next mating season after June, as the spermatozoa may not have an opportunity to fertilize eggs until the next season and there is no sign of spermatozoa absorption in the testis.
  • Y Hayakawa, H Munehara  JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY  295-  (2)  245  -255  2003/11  [Not refereed][Not invited]
     
    To investigate causes of anomalous development of embryos facultatively fertilized in the ovary of a non-copulatory oviparous fish Hemilepidotus gilberti (Scorpaeniformes: Cottdae), dissolved oxygen (DO) concentrations were measured in ovaries of copulatory oviparous (Alcichthys alcicornis, Bero elegans), non-copulatory oviparous (H. gilberti, Hexagrammus otakii), and viviparous (Sebastes taczanowskii, Zoarces elongatus) fishes. DO concentrations changed during vitellogenesis and ovulation cycles, and also before and after ovulation. DO concentrations in the ovary of H. gilberti and H. otakii at ovulation were 0.27 +/- 0.03 and 0.15 +/- 0.03 mg O-2 1(-1), respectively, whereas in A. alcicornis and B. elegans, the concentrations were 0.47 +/- 0.08 and 0.20 +/- 0.06 mg O-2 1(-1), respectively. In the ovaries of intralumenal gestation viviparous fishes, S. taczanowskii and Z. elongatus, DO concentration was from 0.01 to 0.11 mg O-2 1(-1). The average DO concentration during the artificial pregnancy of A. alcicornis was 0.97 +/- 0.19 mg O-2 1(-1), but all embryos showed deformity. DO concentrations recorded in oviparous fishes in this study were lower than the oxygen level at which most oviparous fish embryos exhibit retardation or death, and it probably caused the anomalous embryonic development. In contrast, the normal development of viviparous fish embryos at low oxygen level was attributed to the specialized structure of ovary, e.g. the dual arterial system to supply the developing embryos with the respiratory demands in Sebastes. (C) 2003 Elsevier B.V. All rights reserved.
  • Y Iwata, H Munehara, Y Sakurai  MOLECULAR ECOLOGY NOTES  3-  (3)  392  -393  2003/09  [Not refereed][Not invited]
     
    Loligo bleekeri has a long spawning season and the size of mature males changes during the season: dimorphic (large/small) early in the spawning season and monomorphic (small) later in the spawning season. To understand how copulatory behaviours relate to the dimorphism, we developed five polymorphic microsatellite loci in L. bleekeri. The level of polymorphism ranged from 10 to 22 alleles with expected heterozygosities ranging from 0.79 to 0.93, suggesting that the novel polymorphic loci should be useful for parentage analysis of L. bleekeri.
  • 宗原弘幸  生物工学会誌  81-  (8)  363  -363  2003/08/25  [Not refereed][Not invited]
  • 宗原弘幸  遺伝 別冊  (16)  100  -109  2003/04/10  [Not refereed][Not invited]
  • 宗原 弘幸  生物の科学「遺伝」 別冊  (16)  100  -109,図巻頭4p  2003/04  [Not refereed][Not invited]
  • 阿部拓三, 宗原弘幸  日本水産学会大会講演要旨集  2003-  81  2003/04/01  [Not refereed][Not invited]
  • 阿部拓三, 宗原弘幸  日本水産学会大会講演要旨集  2003-  81  2003/04/01  [Not refereed][Not invited]
  • 細野隆史, 宗原弘幸  日本水産学会大会講演要旨集  2003-  267  2003/04/01  [Not refereed][Not invited]
  • 永井徳子, 成松庸二, 宗原弘幸  日本水産学会大会講演要旨集  2003-  81  2003/04/01  [Not refereed][Not invited]
  • 村花宏史, 宗原弘幸  日本水産学会大会講演要旨集  2003-  35  2003/04/01  [Not refereed][Not invited]
  • 阿部拓三, 宗原弘幸  日本魚類学会年会講演要旨  36th-  16  2003  [Not refereed][Not invited]
  • 阿部拓三, 宗原弘幸  日本水産学会大会講演要旨集  2002-  31  2002/03/30  [Not refereed][Not invited]
  • 宗原弘幸  日本水産学会大会講演要旨集  2002-  295  2002/03/30  [Not refereed][Not invited]
  • 細野隆史, 宗原弘幸  日本水産学会大会講演要旨集  2002-  73  2002/03/30  [Not refereed][Not invited]
  • 細野隆史, 宗原弘幸  日本生態学会大会講演要旨集  49th-  299  2002/03/25  [Not refereed][Not invited]
  • 関勝則, 宗原弘幸, 矢部衛  日本魚類学会年会講演要旨  35th-  11  2002  [Not refereed][Not invited]
  • 岸本雄作, 宗原弘幸  日本魚類学会年会講演要旨  35th-  51  2002  [Not refereed][Not invited]
  • 阿部拓三, 宗原弘幸  日本魚類学会年会講演要旨  35th-  14  2002  [Not refereed][Not invited]
  • 恩地理恵, 宗原弘幸, 古屋康則  日本魚類学会年会講演要旨  35th-  15  2002  [Not refereed][Not invited]
  • Kentaro Nozaki, Hiroshi Morino, Hiroyuki Munehara, Valentina G. Sideleva, Katsuki Nakai, Mitsugu Yamauchi, Olga M. Kozhova, Masami Nakanishi  Limnology  3-  (3)  175  -180  2002  [Not refereed][Not invited]
     
    The composition, biomass, and photosynthetic activity of benthic algal communities were investigated in a littoral zone of the south basin of Lake Baikal in July 1998. A transect survey revealed a vertical transition of the dominant taxonomic groups: Ulothrix and diatoms dominated in the shallowest station (depth, 0.5m), whereas only diatoms were found in a station with a depth of 1 m. In deeper stations (depth, 2-3m), an endemic filamentous green alga, Draparnaldioides baicalensis, was the predominant form, but in addition to this species, Tetraspora and diatoms were also abundant in algal communities collected in the deepest stations (depth, 5-6m). Biomass expressed as chlorophyll a (Chl a) varied in the range of 8 mg Chl a·m-2 (at a depth of 1m) and 300 mg Chl a·m-2 (at a depth of 3m). The maximum photosynthetic rate (of carbon, C) of the community dominated by Ulothrix was 0.24 mg C·mg Ch1 a 1·h 1, whereas the corresponding rate of the community dominated by Draparnaldioides was 1.51 mg C· Ch1 a 1·h1.
  • MUNEHARA Hiroyuki, AWATA Satoshi, KATOH Rei, KOHDA Masanori, SUNOBE Tomoki  Bulletin of Fisheries Sciences, Hokkaido University  52-  (3)  131  -133  2001/12  [Not refereed][Not invited]
  • 細野隆史, 宗原弘幸  日本水産学会大会講演要旨集  2001-  198  2001/04/01  [Not refereed][Not invited]
  • 細野隆史, 宗原弘幸  北海道大学水産科学研究い報  52-  (1)  11  -37  2001/03/27  [Not refereed][Not invited]
     
    ハイマツの冬胞子葉さび病菌Coleosporium pini-pumilaeは,ハイマツの針葉に形成される冬胞子世代のみを有する短世代種と考えられていたが,その証明はなく,さらに精子器形成の有無,感染後の潜伏期間などは不明であった.岩手山の網張国有林で採取した冬胞子から形成された担子胞子によるストローブマツおよびアカマツ新葉への接種試験の結果,10カ月後にストローブマツのみ冬胞子が形成された.以上の結果,本種には精子器は存在せず,冬胞子世代のみをもつ短世代種であることが実験的に証明された.本実験では,被接種植物を平地の苗畑(盛岡市)に置いたため潜伏期間は10カ月であったが,自然発生地での観察から,潜伏期間は2年にわたる場合も多いと考察した.
  • H Munehara, O Takenaka  JOURNAL OF ETHOLOGY  19-  (1)  68  -68  2001  [Not refereed][Not invited]
  • Nagao Jiro, Munehara Hiroyuki  Crust Res  30-  (0)  72  -81  2001  [Not refereed][Not invited]
     
    Annual reproductive cycle of the helmet crab Telmessus cheiragonus was investigated based on the histological observations of the ovary and the gonadosomatic indices (GSI = ovarian weight x 100 / body weight). The ovarian maturity was divided into five phases (Phase I-V). Minimum mature size of female was 36.0 mm in carapace length. The annual reproductive cycle in the adult females (more than 36.0 mm carapace length) consisted of the incubating period (October-March) and the maturing period (April-September). During the incubating period, the ovarian maturity was Phase I-II (mean GSI±SD = 3.8±4.7 %) when most of the females were ovigerous. During the maturing period, the ovarian maturity increased to Phase V (GSI &le; 21.6 %) when the females seemed to be frequently copulating, because the soft shell adult females, which could copulate, occurred with highest frequency. The spawning of most females seemed to occur at the end of the maturing period. These results suggest that the ovarian maturation cycle requires one year, and during the incubation period ovaries are immature.
  • 向田靖子, 宗原弘幸  日本魚類学会年会講演要旨  34th-  25  2001  [Not refereed][Not invited]
  • 阿部拓三, 宗原弘幸  日本魚類学会年会講演要旨  34th-  26  2001  [Not refereed][Not invited]
  • 幸田正典, 安房田智司, 宗原弘幸, 堀道雄  日本魚類学会年会講演要旨  34th-  24  2001  [Not refereed][Not invited]
  • 永井徳子, 成松庸二, 宗原弘幸  日本魚類学会年会講演要旨  34th-  74  2001  [Not refereed][Not invited]
  • 宗原弘幸, MARKEVICH A I  日本魚類学会年会講演要旨  34th-  25  2001  [Not refereed][Not invited]
  • Y Narimatsu, H Munehara  BEHAVIOUR  138-  85  -96  2001/01  [Not refereed][Not invited]
     
    The territoriality of parental males and the hatching late of egg masses in their territories were examined in Hypoptychus dybowskii, a species in which territorial males care for egg masses only just after mating, and sneaker males are known to occur. Most males deserted the territories with egg masses, but the hatching rates of abandoned and attended egg masses were similar. A large percentage of the deserted territories with egg masses were taken over by non-territorial males. Comparison of the mating success between males that deserted territories and those that attended territories showed that territory desertion occurred when males experienced fewer chances to mate. These results indicate that territorial males contributed little to embryonic survivorship after egg mass hardening, and deserted their territories depending on the mating rate. Such an unique reproductive strategy may be adaptive when there are no parental costs after arrangement of egg masses, high hatching rates of abandoned egg masses, and a high chance of sneaking.
  • Y Hayakawa, H Munehara  JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY  256-  (1)  51  -58  2001/01  [Not refereed][Not invited]
     
    Fertilized residual eggs were observed in the ovaries of spent females of a non-copulatory sculpin Hemilepidotus gilberti Jordan and Starks. Fertilized eggs were present in 23 of 35 females, and approximately 38% of the total residual eggs (n = 227) were fertilized. These eggs were thought to be fertilized facultatively with spermatozoa that entered the ovary through ovarian fluid during spawning. The high calcium concentration (1.42+/-0.21 mM kg(-1)) in ovarian fluid, which is beyond the threshold concentration required for fertilization, may anew internal fertilization to occur. Embryos at various developmental stages were observed, but all were deformed and surrounded by unhardened chorions. Since no larvae were observed, all the fertilized residual eggs would have degenerated in the ovary in accordance with other unfertilized residual eggs. These observations suggest that the ovary of the oviparous fish H. gilberti is an unsuitable environment for embryos to develop, possibly because it may be unable to supply developing embryos with needed elements, such as oxygen. (C) 2001 Elsevier Science B.V. All rights reserved.
  • H Munehara, Z Kanamoto, T Miura  ICHTHYOLOGICAL RESEARCH  47-  (3)  287  -292  2000/08  [Not refereed][Not invited]
     
    The spawning behavior of Hexagrammos otakii, H. octogrammus and H. agrammus was observed in two different regions of northern Japan using underwater video cameras placed near nests guarded by males. The spawning behavior of the three species consisted of similar patterns, although body size and nuptial coloration and nest location of territorial male H. otakii differed from those of the other two Hexagrammos species. The courtship display of territorial males in each species involved rushing, butting and undulation of the trunk. When a female entered the nest, the male leaned his head on the future spawning bed in the nest and spasmodically undulated his trunk. The female that responded to the courtship laid her eggs within the seaweed bed. The territorial male then passed over the eggs, touching his genital pore to the egg mass, and released sperm. Sneaking by other males was frequently observed following the sperm emission. In both regions, females of H. octogrammus and H. agrammus commonly responded to courtship of male H. otakii and mated with them, but not vice versa. Possible reasons for the natural occurrence of such unidirectional hybridization are discussed.
  • 永尾次郎, 神尾道也, 宗原弘幸  日本水産学会大会講演要旨集  2000-  81  2000/04/01  [Not refereed][Not invited]
  • 後藤晃, 宗原弘幸, 森野浩, SIDELEVA V G  日本魚類学会年会講演要旨  33rd-  21  2000  [Not refereed][Not invited]
  • 宗原弘幸, SIDELEVA V G, 後藤晃  日本魚類学会年会講演要旨  33rd-  21  2000  [Not refereed][Not invited]
  • 加藤励, 幸田正典, 宗原弘幸  日本魚類学会年会講演要旨  33rd-  30  2000  [Not refereed][Not invited]
  • 成松庸二, 宗原弘幸  日本魚類学会年会講演要旨  33rd-  24  2000  [Not refereed][Not invited]
  • 矢部衛, 篠原現人, 宗原弘幸, 鈴木伸明, PITRUK D L, SOKOLOVSKY A S, MARKEVICH A I, CHERESHNEV I, NAZARKIN M  Orig Biodivers Fishes Far East Russ North Jpn  61  -69  2000  [Not refereed][Not invited]
  • H Munehara, O Takenaka  JOURNAL OF ETHOLOGY  18-  (2)  101  -104  2000  [Not refereed][Not invited]
     
    The fertilization success of sneaking behavior in a paternal care fish, Hexagrammos otakii, was estimated using microsatellites as genetic markers. Sneaking behavior was observed using a video camera placed near the nest of a breeding territorial male. Two egg masses fertilized by different patterns of sperm Emission by the territorial male and sneaker males were examined for paternity discrimination. When a sneaker emitted a large amount of sperm after sperm emission by the territorial male, the sneaker fertilized more eggs than the territorial male. When the territorial male and a sneaker alternately emitted semen, the territorial male fertilized the most eggs. These results suggest that both the amount of emitted sperm and the timing of sperm emission are important factors in sperm competition.
  • 宮城真琴, 宗原弘幸, 岩本欣也, 筒井昭光  日本太陽エネルギー学会・日本風力エネルギー協会合同研究発表会講演論文集  1999-  137  -140  1999/11/25  [Not refereed][Not invited]
  • J Nagao, H Munehara, K Shimazaki  JOURNAL OF CRUSTACEAN BIOLOGY  19-  (1)  77  -83  1999/02  [Not refereed][Not invited]
     
    External morphological changes in embryos of the hair crab Erimacrus isenbeckii (Brandt) reared in the laboratory were observed. Embryonic development was divided into 9 stages based on morphological changes: precleavage stage, cleavage and blastula stage, gastrula stage, naupliar stage, metanaupliar stage, pigmented-eye stage, heartbeat-initiation stage, prezoea stage, and prehatching stage. Embryos spawned by a female in January developed to the gastrula stage by March. Embryos from another female developed from the gastrula stage to the prehatching stage from March to December, and hatched in January. These results suggest that the incubation period under laboratory conditions was about 12 months. Since one female collected in February still carried prezoea-stage embryos, the embryonic growth rate in the laboratory was expected to be higher than in the field. It is thought that the length of the incubation period is affected by many environmental factors, but the embryonic growth rate is mainly controlled by water temperature. Thus, around Hukkaido, where specimens studied were collected, incubating females may be distributed in temperatures cooler than in the laboratory.
  • Yoji Narimatsu, Hiroyuki Munehara  Canadian Journal of Fisheries and Aquatic Sciences  56-  1849  -1855  1999/01/01  [Not refereed][Not invited]
     
    The effects of spawn date on survival and growth during the embryonic, larval, and juvenile stages of a coastal fish, Hypoptychus dybowskii (Gasterosteiformes), were examined. Monitoring of embryos using SCUBA showed that the embryonic period decreased as the season progressed and the hatching rate was lowest for the early-spawn cohort (EC). Analysis of otolith daily growth increments indicated that EC larvae had much lower survival and growth rates than larvae of middle-spawn (MC) and late-spawn cohorts (LC), but there were no large differences in either rate among juveniles of the three cohorts. EC suffered the highest mortality rates in the embryonic and larval stages; these high rates were linked with slow development and growth, probably caused by below-optimum water temperatures. EC fish grew over a longer period and reached larger body size than MC and LC fish. These results suggest that intraannual variations in growth pattern and survival rate in the embryonic and larval stages were caused by spawn date differences, which favored the LC in the study year, but the EC might have a size-dependent advantage in survivorship and reproductive success during the postjuvenile stages.
  • 永尾次郎, 宗原弘幸  日本水産学会大会講演要旨集  1998-  46  1998/04  [Not refereed][Not invited]
  • Y Koya, H Munehara, K Takano  JOURNAL OF MORPHOLOGY  233-  (2)  153  -163  1997/08  [Not refereed][Not invited]
     
    The morphology of female sperm storage during the spawning period and the morphology of sperm degradation after the spawning period were investigated by electron microscopy in a copulating teleost, Alcichthys alcicornis. The spermatozoa were maintained in the ovarian cavity, floating in the ovarian fluid during the spawning period. The spermatozoa then degenerated and were phagocytized by macrophages invading the ovarian cavity after the spawning period. In the ovary during the spawning period, horseradish peroxidase used as a tracer revealed tight junctional complexes connecting adjacent cells of the inner ovarian epithelia (ovarian wall epithelium and ovigerous lamella epithelium). This indicates that a compartmentalization of the ovarian cavity occurs during the spawning period. The junctional complexes were breached after the spawning period, as shown by the fact that horseradish peroxidase penetrated the ovarian cavity via the intercellular space between the adjoining ovigerous lamella epithelia. These results suggest that the spermatozoa in the ovarian cavity are isolated from the maternal immune system by the tight junctional complexes between the adjoining inner ovarian epithelia during the spawning period, and then are eliminated by immune cells following the breakdown of the junctional complexes after the spawning period. (C) 1997 Wiley-Liss, Inc.
  • MUNEHARA Hiroyuki, TAKENAKA Osamu  DNA多型 = DNA polymorphism  5-  218  -222  1997/07/31  [Not refereed][Not invited]
  • H Munehara  FISHERY BULLETIN  95-  (3)  612  -619  1997/07  [Not refereed][Not invited]
  • 永尾次郎, 宗原弘幸  日本水産学会大会講演要旨集  1997-  45  1997/04  [Not refereed][Not invited]
  • 宗原弘幸, 金本自由生  日本水産学会大会講演要旨集  1997-  85  1997/04  [Not refereed][Not invited]
  • 早川洋一, 古丸明, 宗原弘幸  日本水産学会大会講演要旨集  1997-  86  1997/04  [Not refereed][Not invited]
  • 成松庸二, 宗原弘幸  日本水産学会大会講演要旨集  1997-  86  1997/04  [Not refereed][Not invited]
  • H Munehara, Y Koya, Y Hayakawa, K Takano  JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY  211-  (2)  279  -289  1997/04  [Not refereed][Not invited]
     
    Conditions for the initiation of fertilization and the initial fertilization process were investigated using histological observations of eggs of Hemitripterus villosus (Pallas), an oviparous fish that undergoes internal insemination. Eggs obtained from ovaries of inseminated females already had spermatozoa present inside the micropylar canal, but showed no signs of fertilization. The contents of the cortical alveolae were discharged after the eggs were immersed in seawater, suggesting that fertilization is initiated after spawning. These observations indicate that the spawning mode of H. villosus is one of internal gametic association with external fertilization, as previously reported in Alcichthys alcicornis and Blepsias cirrhosus. Fertilization occurred in an isotonic media rich in calcium ions. Calcium ion concentration of the ovarian fluid of H. villosus was lower than that of the media in which fertilization occurred. These results suggest the failure to initiate fertilization internally was caused by a deficiency of calcium ions in the ovarian fluid. The plug-like structure in the outer opening of the micropylar canal appeared 10 min after the eggs' immersion in seawater. The plug-like structure appears to originate from irregular particles dispersed on the vestibule. Another plug-like structure appeared in the inner opening of the micropylar canal 2 h after the eggs' immersion in seawater. Rather than blocking polyspermy, the two plug-like structure probably prevent foreign micro-organisms from invading the ooplasm during the long embryonic period (4 months). (C) 1997 Elsevier Science B.V.
  • LIU Haijin, SAKURAI Yasunori, MUNEHARA Hiroyuki, TAKEYAMA Syuichi, SHIMAZAKI Kenji  水産増殖  45-  (1)  81  -86  1997/03/20  [Not refereed][Not invited]
  • LIU Haijin, SAKURAI Yasunori, MUNEHARA Hiroyuki, TAKEYAMA Syuichi, SHIMAZAKI Kenji  Aquaculture Sci.  45-  (1)  81  -86  1997  [Not refereed][Not invited]
     
    The rates of oxygen consumption and ammonia excretion after feeding of the Japanese flounder <I>Paralichthys olivaceus</I> were measured over a 24-hour period for a group fed once at 09: 00 hours and a group fed once at 18: 00 hours. The specific dynamic action (SDA) magnitudes of the two groups after feeding were not significantly different, but they showed different patterns during the experimental period. The peak level of oxygen consumption for the group fed at 18: 00 hours was 24.5 % higher than that of the group fed at 09: 00 hours. There were no significant differences between either the peak ammonia excretion rate for each group or between the mean ammonia excretion rate for each group. A single peak in ammonia excretion occurred 3-6 hours after feeding for both groups during the 24-hour experimental period. The rate of ammonia excretion returned to the pre-feeding level approximately 24 hours after feeding.
  • 成松庸二, 宗原弘幸  日本魚類学会年会講演要旨  30th-  39  1997  [Not refereed][Not invited]
  • Yoji Narimatsu, Hiroyuki Munehara  Fisheries Science  63-  503  -508  1997/01/01  [Not refereed][Not invited]
     
    Age and daily growth of Hypoptychus dybowskii collected periodically off Usujiri, southern Hokkaido, June 1993 to June 1994, were investigated using otolith-increment counts. Daily increment formation was verified by comparing the number of increments formed after alizarin complexone marking with the number of days after treatment. Most growth occurs during the first 6 months from hatching. The relationship between standard length and the number of daily growth increments was best fitted to a Logistic curve for male, and a Gompertz curve for females: (males) Lt = 56.25/(1 + exp-0.034(t - 68.00)) and (females) Lt = 63.16 exp-exp-0.018(t - 54.98)No specimen had more than 365 increments in its sagittae, suggesting this species has a life span of one year.
  • R. A. Khan, H. Munehara, K. Ryan, J. W. Lawson  Canadian Journal of Zoology  75-  1280  -1284  1997/01/01  [Not refereed][Not invited]
     
    A study was conducted to determine the prevalence and effects of two species of blood-feeding copepods on their definitive fish hosts, viz. Haemobaphes cyclopterina parasitizing Arctic cod (Boreogadus saida) and H. intermedius infecting tidepool soulpins (Oligocottus maculosus). Infected and uninfected Arctic cod and tidepool sculpins were captured by SCUBA and dip net in the northwest Atlantic and northeast Pacific, respectively. Biological variables such as condition factor, hepatic somatic index, gonadal somatic index, and haematocrit were compared between the two groups of Arctic cod of both sexes, whereas only condition factor was compared in the two groups of sculpins of both sexes. Prevalence of H. cyclopterina (8%) was considerably lower than that of H. intermedius (46%). This difference is probably associated with the hosts' behaviour, as the Arctic cod is pelagic whereas the tidepool sculpin is restricted to the littoral zone, where infections are probably acquired. Infected Arctic cod of both sexes had significantly lower condition factor, hepatic and gonadal somatic indices, and haematocrit than non-parasitized fish. Only females harboured large numbers of the parasite and showed even more dramatic changes than the corresponding groups. The growth period of H. cyclopterina on Arctic cod from the time of infection to the fully developed egg sac stage is probably about 6 months. In tidepool sculpins, condition factor was significantly lower in infected than in uninfected fish. These results, especially for the Arctic cod, parallel those reported for gadoid fish following infection with haematophagous species of Lernaeocera that impair growth and reproduction.
  • 早川洋一, 宗原弘幸  日本水産学会大会講演要旨集  1996-  33  1996/03  [Not refereed][Not invited]
  • 宗原弘幸, 三浦汀介  日本水産学会大会講演要旨集  1996-  45  1996/03  [Not refereed][Not invited]
  • 成松庸二, 宗原弘幸, 島崎健二  日本水産学会大会講演要旨集  1996-  51  1996/03  [Not refereed][Not invited]
  • 永尾次郎, 宗原弘幸  日本水産学会大会講演要旨集  1996-  34  1996/03  [Not refereed][Not invited]
  • Y Hayakawa, H Munehara  ICHTHYOLOGICAL RESEARCH  43-  (1)  73  -78  1996/02  [Not refereed][Not invited]
     
    The reproductive behavior of a marine sculpin, Hemilepidotus gilberti, was observed in the aquarium. The behavioral sequence comprised fight for territory, courtship and fight for females, spawning and caring for the egg mass. Females very slowly deposited eggs enclosed with viscous ovarian fluid onto the substrate. Almost all the eggs contained in the ovary were released in a single spawning, its completion requiring 21-52 min. Territorial males emitted semen against the deposited eggs, about 6 and 11 min after the beginning of spawning. Sneaking by neighboring males followed subsequently. This was the first observation of non-copulatory spawning among marine sculpins. Females cared for the eggs for several days after spawning, and then male alone care continued until hatching (47-49 days after spawning). Participation by females in egg caring is likely to be caused by their spawning only once during the spawning season and the consequent lack of urgency for post-spawning feeding.
  • 早川洋一, 秋山良, 古丸明, 宗原弘幸  日本魚類学会年会講演要旨  29th-  56  1996  [Not refereed][Not invited]
  • 成松庸二, 宗原弘幸, 島崎健二  日本魚類学会年会講演要旨  29th-  54  1996  [Not refereed][Not invited]
  • 宗原弘幸, 竹中修  日本魚類学会年会講演要旨  29th-  56  1996  [Not refereed][Not invited]
  • H Munehara, T Miura  JOURNAL OF ETHOLOGY  13-  (2)  191  -193  1995/12  [Not refereed][Not invited]
  • Y KOYA, H MUNEHARA, K TAKANO  JAPANESE JOURNAL OF ICHTHYOLOGY  42-  (1)  45  -52  1995/05  [Not refereed][Not invited]
     
    Formation of the vitelline envelope of the masked greenling was investigated by electron microscopy to clarify the origin of adhesive material on the chorion. In developing oocytes the envelope had three zones, referred to as Z1 (outermost), Z2 and Z3. Z1 and Z2 first appeared during the pre-vitellogenic stage. Z1 consisted of a low electron-dense substance accumulated in the space between Z2 an electron-dense substance deposited on the oocyte surface and the granulosa cells. During this stage, well developed endoplasmic reticula and Golgi apparati occurred in the granulosa cells. Numerous small vesicles in the granulosa cell fused with the plasma membrane facing the oocyte. Therefore, it is plausible that the granulosa cell synthesizes and secrets some material for Z1, which formed continuously until the vitellogenic stage, when formation of Z3 occurred. In pre-ovulatory follicles, the structure of Z1 changed greatly, the major portion of its constituents diffusing into the wide intercellular spaces between the granulosa cells. The remaining portion of Z1 was transformed into fine coagulative particles forming a thin, down-like layer. In ovulated eggs, a transparent layer appearing on the outside of the down-like layer was considered to have formed from the diffused portion of the Z1 components, which coagulated and then swelled by absorbing ovarian fluid. The transparent layer disappeared after the egg was immersed in seawater, allowing the exposed, down-like layer to adhere directly to adjacent eggs.
  • Y KOYA, H MUNEHARA, K TAKANO  JAPANESE JOURNAL OF ICHTHYOLOGY  42-  (1)  45  -52  1995/05  [Not refereed][Not invited]
     
    Formation of the vitelline envelope of the masked greenling was investigated by electron microscopy to clarify the origin of adhesive material on the chorion. In developing oocytes the envelope had three zones, referred to as Z1 (outermost), Z2 and Z3. Z1 and Z2 first appeared during the pre-vitellogenic stage. Z1 consisted of a low electron-dense substance accumulated in the space between Z2 an electron-dense substance deposited on the oocyte surface and the granulosa cells. During this stage, well developed endoplasmic reticula and Golgi apparati occurred in the granulosa cells. Numerous small vesicles in the granulosa cell fused with the plasma membrane facing the oocyte. Therefore, it is plausible that the granulosa cell synthesizes and secrets some material for Z1, which formed continuously until the vitellogenic stage, when formation of Z3 occurred. In pre-ovulatory follicles, the structure of Z1 changed greatly, the major portion of its constituents diffusing into the wide intercellular spaces between the granulosa cells. The remaining portion of Z1 was transformed into fine coagulative particles forming a thin, down-like layer. In ovulated eggs, a transparent layer appearing on the outside of the down-like layer was considered to have formed from the diffused portion of the Z1 components, which coagulated and then swelled by absorbing ovarian fluid. The transparent layer disappeared after the egg was immersed in seawater, allowing the exposed, down-like layer to adhere directly to adjacent eggs.
  • 早川洋一, 宗原弘幸, 島崎健二  日本水産学会大会講演要旨集  1995-  104  1995/04  [Not refereed][Not invited]
  • 劉海金, 桜井泰憲, 宗原弘幸, 島崎健二  日本水産学会大会講演要旨集  1995-  51  1995/04  [Not refereed][Not invited]
  • 永尾次郎, 宗原弘幸, 島崎健二  日本水産学会大会講演要旨集  1995-  86  1995/04  [Not refereed][Not invited]
  • 成松庸二, 宗原弘幸, 島崎健二  日本水産学会大会講演要旨集  1995-  124  1995/04  [Not refereed][Not invited]
  • 宗原弘幸  日本魚類学会年会講演要旨  28th-  31  1995  [Not refereed][Not invited]
  • H MUNEHARA, A TAKENAKA, O TAKENAKA  JOURNAL OF ETHOLOGY  12-  (2)  115  -120  1994/12  [Not refereed][Not invited]
     
    The elkhorn sculpin Alcichthys alcicornis spawns and subsequently copulates, and the eggs are then cared for by the male. DNA fingerprinting was used to determine the paternity of males for the clutches guarded by them. When a female was mated with 4 males in succession in aquaria, males did not fertilize the eggs spawned just before copulation unless the female was unimpregnated but fathered the eggs spawned by the female later. In the field, near the end of the breeding season, males were genetically unrelated to the clutches in their territories. We concluded that males guard non-kin eggs for the opportunity to copulate and to fertilize the future clutches of their mates.
  • H MUNEHARA, JM PAUL, AJ PAUL  JAPANESE JOURNAL OF ICHTHYOLOGY  41-  (1)  73  -75  1994/05  [Not refereed][Not invited]
     
    Resurrection Bay, near Seward, Alaska, is one of many glacially influenced fjords that exist along the northern Gulf of Alaska. No ichthyofaunal surveys have been carried out in the region and as a result the noncommercial fish fauna is poorly described. Collections of ichthyoplankton during a biological study of commercial fishes provided this opportunity to describe for the first time the Scorpaeniformes larvae present during spring, providing some information into the species in this group that inhabit the fjord.
  • Y KOYA, H MUNEHARA, K TAKANO  JAPANESE JOURNAL OF ICHTHYOLOGY  41-  (1)  39  -45  1994/05  [Not refereed][Not invited]
     
    Histological observations of the ovaries, statistical analyses Of catches by trammel net, and observations of territorial males and egg masses by SCUBA diving were made in order to clarify the reproductive biology of the elkhorn sculpin, Alcichthys alcicornis. Ovarian development was categorized as immature (July-December), yolk accumulation (January-March), copulation and spawning (April-May), or degeneration (May-June). Sections taken from mature ovaries showed A. alcicornis to be a multiple spawner, ovulating and spawning several times in a single breeding season. Trammel net catches during the breeding season suggested that members of the breeding population migrate synchronously by sex from offshore depths to shallow waters, males preceding females by 1 week (in late March-mid April); females achieve initial spawning by late April. Breeding sites were found in cracks or crevices between rocks within territories established by territorial males. At least 80-100 egg masses were deposited in each territory during the overall spawning season. The occurrence or otherwise of sneaking tactics during copulation in A. alcicornis is discussed.
  • H MUNEHARA, JM PAUL, AJ PAUL  JAPANESE JOURNAL OF ICHTHYOLOGY  41-  (1)  73  -75  1994/05  [Not refereed][Not invited]
  • Y KOYA, H MUNEHARA, K TAKANO  JAPANESE JOURNAL OF ICHTHYOLOGY  41-  (1)  39  -45  1994/05  [Not refereed][Not invited]
     
    Histological observations of the ovaries, statistical analyses Of catches by trammel net, and observations of territorial males and egg masses by SCUBA diving were made in order to clarify the reproductive biology of the elkhorn sculpin, Alcichthys alcicornis. Ovarian development was categorized as immature (July-December), yolk accumulation (January-March), copulation and spawning (April-May), or degeneration (May-June). Sections taken from mature ovaries showed A. alcicornis to be a multiple spawner, ovulating and spawning several times in a single breeding season. Trammel net catches during the breeding season suggested that members of the breeding population migrate synchronously by sex from offshore depths to shallow waters, males preceding females by 1 week (in late March-mid April); females achieve initial spawning by late April. Breeding sites were found in cracks or crevices between rocks within territories established by territorial males. At least 80-100 egg masses were deposited in each territory during the overall spawning season. The occurrence or otherwise of sneaking tactics during copulation in A. alcicornis is discussed.
  • Hiroyuki Munehara, Yasunori Koya, Kazunori Takano  Journal of Fish Biology  45-  (6)  1105  -1111  1994  [Not refereed][Not invited]
     
    The reason for failure to initiate fertilization internally was examined in a cottid fish, the elkhorn sculpin, Alcichthys alcicornis which has internal gametic association and external fertilization. While eggs could be activated in calcium free hypertonic media but not be fertilized, fertilization occurred in isotouic media rich in calcium ions. The rate of fertilization was dependent on calcium concentration, and eggs were not fertilized in solutions with a calcium ion concentration of less than 0·57 mmol kg−1. Calcium ions could be replaced to some extent by magnesium ions, but the former were the more effective in fertilization. Since calcium ion concentration of ovarian fluid of A. alcicornis was 0·41 mmol kg−1, it was inferred that low calcium concentration in the ovarian fluid was the cause of the failure of A. alcicornis eggs to fertilize internally. Copyright © 1994, Wiley Blackwell. All rights reserved
  • Y KOYA, H MUNEHARA, K TAKANO  JAPANESE JOURNAL OF ICHTHYOLOGY  40-  (2)  199  -208  1993/08  [Not refereed][Not invited]
     
    Examination was made of the ultrastructure of the epithelial lining of the ovarian wall and the ovigerous lamellae in the ovary of female masked greenling, Hexagrammos octogrammus, to determine the origin of the jelly-like ovarian fluid present in the ovarian lumen during the spawning period. The surface of the ovarian wall and ovigerous lamellae were each covered with monolayered epithelium resting on the basement membrane. During the spawning period, microvilli were present on the apical surface, and remarkable increases in mitochondria, rough-surfaced endoplasmic reticula and Golgi apparati were noted. Many secretory vesicles were separate from the Golgi apparatus. Microapocrine secretion and exocytosis occurred at the tips and basal parts of the microvilli, respectively, throughout the spawning period. In one case macroapocrine secretion from the ovarian wall epithelium was observed and is suggested as representing the time of most active secretion. The endocytotic uptake of secretory substances at the basal and lateral parts of the epithelium was evident from an experiment using horseradish peroxidase as a tracer. The results indicated that the components of the jelly-like ovarian fluid are synthesized and secreted not only from ovarian wall epithelium, but also from ovigerous lamella epithelium, the modes of secretion from these epithelia comprising microapocrine, macroapocrine and exocytotic mechanisms.
  • Y KOYA, H MUNEHARA, K TAKANO  JAPANESE JOURNAL OF ICHTHYOLOGY  40-  (2)  199  -208  1993/08  [Not refereed][Not invited]
     
    Examination was made of the ultrastructure of the epithelial lining of the ovarian wall and the ovigerous lamellae in the ovary of female masked greenling, Hexagrammos octogrammus, to determine the origin of the jelly-like ovarian fluid present in the ovarian lumen during the spawning period. The surface of the ovarian wall and ovigerous lamellae were each covered with monolayered epithelium resting on the basement membrane. During the spawning period, microvilli were present on the apical surface, and remarkable increases in mitochondria, rough-surfaced endoplasmic reticula and Golgi apparati were noted. Many secretory vesicles were separate from the Golgi apparatus. Microapocrine secretion and exocytosis occurred at the tips and basal parts of the microvilli, respectively, throughout the spawning period. In one case macroapocrine secretion from the ovarian wall epithelium was observed and is suggested as representing the time of most active secretion. The endocytotic uptake of secretory substances at the basal and lateral parts of the epithelium was evident from an experiment using horseradish peroxidase as a tracer. The results indicated that the components of the jelly-like ovarian fluid are synthesized and secreted not only from ovarian wall epithelium, but also from ovigerous lamella epithelium, the modes of secretion from these epithelia comprising microapocrine, macroapocrine and exocytotic mechanisms.
  • Yasunori Koya, Hiroyuki Munehara, Kazunori Takano, Hiroya Takahashi  Comparative Biochemistry and Physiology -- Part A: Physiology  106-  (1)  25  -29  1993  [Not refereed][Not invited]
     
    1. 1. The motility of spermatozoa in several marine sculpins, which exhibit a special reproductive manner of the internal gametic association, was measured in various artificial solutions, ovarian fluid and seminal plasma. 2. 2. In the elkhorn sculpin, Alcichthys alcicornis, spermatozoa showed high motility in solutions of 300 to 400 mOsm/kg, containing sodium ion, with pH higher than 7.5, which coincided with the nature of ovarian fluid of the fish. 3. 3. Spermatozoa of sunrise sculpin, Pseudoblennius cottoides, and elegant sculpin, Bero elegans, were motile at osmolalities isotonic to the ovarian fluid but not at osmolalities higher than 500 and 800 mOsm/kg, respectively, indicating that the gametic association in these fish is carried out exclusively in their ovaries. 4. 4. Spermatozoa of littledragon sculpin, Blepsias cirrhosus, were motile at osmolalities higher than 300 mOsm/kg, but not in sea water, suggesting an internal gametic association to occur in this species of sculpins. 5. 5. The results indicate that spermatozoa of the marine sculpins with the internal gametic association show their motility in environmental conditions appropriate to respective reproductive modes. © 1993.
  • Hiroyuki Munehara  Environmental Biology of Fishes  33-  (4)  395  -398  1992/04  [Not refereed][Not invited]
     
    The sea raven, Hemitripterus villosus, deposits its eggs on polychaete tubes (Salmacina sp.) in the coastal waters of Usujiri, southern Hokkaido, Japan. This is contradictory to investigations in the Bay of Peter the Great, Soviet Union, where eggs are deposited in narrow clefts. The egg masses are found among the bunchy worm tubes or between the base of the colony and the substrate. The spawning habit of H. villosus is distinct from 'spawner in live invertebrates' such as the little dragon sculpin Blepsias cirrhosus, which specifically associates with a sponge. That of H. villosus is classified as a 'cavity spawner'. © 1992 Kluwer Academic Publishers.
  • Hiroyuki Munehara, Kazunori Takano, Yasunori Koya  Japanese Journal of Ichthyology  37-  (4)  391  -394  1991/12  [Not refereed][Not invited]
     
    In the copulating cottid species, Blepsias cirrhosus, the point at which fertilization occurred was determined experimentally. Ovulated eggs were obtained directly from the ovary of impregnated females. Eggs maintained in ovarian fluid did not show any signs of development, whereas most of the eggs which had been placed in seawater had developed to the 4-cell stage after 24hrs. The eggs kept in ovarian fluid initiated segmentation when later transferred into seawater. Histological examination showed that a number of spermatozoa had entered the micropyle, but that penetration did not occur in eggs that were not immersed in seawater. In these eggs, the metaphase spindle of the second meiotic division was observed in the ooplasm, at the animal pole. These results indicate that, in impregnated females, the spermatozoa associate with the eggs in the ovarian cavity, but that fertilization occurs externally when the eggs are spawned. © 1991 The Ichthyological Society of Japan.
  • MUNEHARA H  Japanese journal of ichthyology  38-  (2)  p179  -184  1991/10  [Not refereed][Not invited]
  • 宗原 弘幸, 島崎 健二  魚類学雑誌  38-  (1)  p31  -34  1991/06  [Not refereed][Not invited]
  • Hiroyuki Munehara  Japanese Journal of Ichthyology  38-  (2)  179  -184  1991/06  [Not refereed][Not invited]
     
    It was established that the little dragon sculpin Blepsias cirrhosus uses the sponge species Mycale adhaerens as a spawning bed. The eggs were completely concealed in the sponge tissues, and caused the sponge skeleton to be partly damaged. It is conceivable that the exclusive utilization of M. adhaerens by B. cirrhosus is a consequence of the advantageous softness and thickness of the sponge which allows the fish to inject the eggs. The eggs deposited in the sponge seemed to take advantage of predator avoidance, a constant supply of oxygen, and little interference by bacteria. © 1991 The Ichthyological Society of Japan.
  • H MUNEHARA, K SHIMAZAKI  JAPANESE JOURNAL OF ICHTHYOLOGY  38-  (1)  31  -34  1991/06  [Not refereed][Not invited]
     
    This paper describes both embryonic development and newly hatched larval morphology of the little dragon sculpin Blepsias cirrhosus. The eggs of B. cirrhosus are almost spherical, 3.0-3.2 mm in diameter, and have a yolk color of burnt orange. Development is very slow, being especially sluggish once the embryo appears. The embryo begins forming from the 10th day. In size, the early embryo is less than 1/6 of the yolk's circumference. Incubation at 10-degrees-C takes about 200 days, 50 days shorter than the incubation period in a natural environment, with a mean water temperature of 11-degrees-C. The notochord length of newly-hatched larvae averages 11.1 mm. The larvae are developed so fully that the notochord is already flexing and the caudal and pectoral rays are forming.
  • H MUNEHARA, K TAKANO, Y KOYA  JAPANESE JOURNAL OF ICHTHYOLOGY  37-  (4)  391  -394  1991/02  [Not refereed][Not invited]
     
    In the copulating cottid species, Blepsias cirrhosus, the point at which fertilization occurred was determined experimentally. Ovulated eggs were obtained directly from the ovary of impregnated females. Eggs maintained in ovarian fluid did not show any signs of development, whereas most of the eggs which had been placed in seawater had developed to the 4-cell stage after 24 hrs. The eggs kept in ovarian fluid initiated segmentation when later transferred into seawater. Histological examination showed that a number of spermatozoa had entered the micropyle, but that penetration did not occur in eggs that were not immersed in seawater. In these eggs, the metaphase spindle of the second meiotic division was observed in the ooplasm, at the animal pole. These results indicate that, in impregnated females, the spermatozoa associate with the eggs in the ovarian cavity, but that fertilization occurs externally when the eggs are spawned.
  • H MUNEHARA, H OKAMOTO, K SHIMAZAKI  JOURNAL OF ETHOLOGY  8-  (1)  21  -24  1990/06  [Not refereed][Not invited]
     
    In Alcichthys alcicornis, a sculpin copulating in conjunction with paternal care, the genetic relation between males and egg masses they guard was investigated using polymorphism of an isozyme. At least 3 out of the 10 egg masses investigated were not genetically related with the guarding males. In these 3 cases, the female parents must have copulated with males other than the guarding males. It was hypothesized that males take care of non-kin eggs for the opportunity to fertilize the next clutch females will produce. © 1990 Japan Ethological Society.
  • Hiroyuki Munehara, Kenji Shimazaki  Nippon Suisan Gakkaishi (Japanese Edition)  55-  (3)  423  -429  1989  [Not refereed][Not invited]
     
    Histological observations were carried out on the ovaries of masked greenling Hexagrammos octogrammus collected in Usujiri, southern Hokkaido, Japan, for the purpose of clarifying the annual reproductive cycle and the first maturational process. The development of ovaries during maturation was divided into the following six phases (1) recovery phase (immature phase in case of under-spawners), (2) pre-vitellogenic phase, (3) vitellogenic phase, (4) maturing phase, (5) early spawning phase, (6) late spawning phase. The vitellogenic phase proceeded for a single month (mid August—mid September), as did the spawning phase (late September—late October). There were three characteristic features in the mode of oocyte development. The first feature was the transference from the peri-nucleolus stage to the yolk vesicle stage had finished when the most advanced oocytes in an ovary were at the migratory nucleus stage. Second, the maturing through the migration of nucleus to the ovulation progressed intermittently as a clutch. The third feature was oocytes at the oil droplet stage, the early yolk globule stage and the late yolk globule stage began degenerating while the last clutch in this spawning period was at the pre-mature or more developing stage. © 1989, The Japanese Society of Fisheries Science. All rights reserved.
  • MUNEHARA H  Japanese journal of ichthyology  35-  (3)  p358  -364  1988/12  [Not refereed][Not invited]
  • Munehara Hiroyuki  JJI  35-  (3)  358  -364  1988  [Not refereed][Not invited]
     
    The spawning and subsequent copulating behavior of the elkhorn sculpin (<I>Alcichthys alcicornis</I>) were observed in an aquarium. Soon after the female was introduced into the tank, the male approached and initiated courtship behavior by unfolding all fins. Females which carried ovulated eggs eventually accepted the male and spawning progressed. Females which had not ovulated, repeatedly rejected the male's advances. The onset of spawning in the female was indicated by fluttering of the pectoral fins and successive horizontal undulations of the posterior trunk which served to sweep the spawning site. The laying of several thousand eggs was preceded by the female taking several large inhalations of water through the mouth and a slight raising of the posterior trunk. The male continued various behavior related to courtship while the female approached spawning. After spawning, the female smoothed the egg mass into a thin layer by using the posterior trunk and anal fin. After spawning, and while the female flattened the egg mass, the male copulated repeatedly. No copulation was observed prior to spawning. Semen was observed to be emitted from the tip of the penis and to leak from the female's genital pore. Eggs were fertilized externally by the emitted sperm in the case of females which had no prior copulating experience in the present breeding season. The entire reproductive behavior of the pair ceased, as the female left the spawning site after flattening the egg mass. The male remained near by, but did not aerate the eggs. During the breeding season, the area around the female's genital pore and along both sides near the base of the anal fin became slightly distended and soft by the accumulation of a serous fluid. It is presumed that this edematous modification serves to flatten the egg mass for softness without crushing the eggs.
  • MUNEHARA H  Bulletin of the Faculty of Fisheries,Hokkaido University  38-  (1)  p27  -33  1987/02  [Not refereed][Not invited]
  • 宗原 弘幸, 三島 清吉  魚類学雑誌  33-  (1)  p46  -50  1986/05  [Not refereed][Not invited]
  • H MUNEHARA, S MISHIMA  JAPANESE JOURNAL OF ICHTHYOLOGY  33-  (1)  46  -50  1986/05  [Not refereed][Not invited]
     
    The eggs of <I>Alcichthys alcicornis</I> were spawned in tank at the laboratory and reared for the studies of embryonic, larval and juvenile development. This species takes place entosomatic fertilization, and females spawn fertilized eggs after copulation. The eggs are demersal and adhesive, released as a clump forming a thin layer on the bottom of tank. There was no significant difference in embryonic development between this species and other oviparous teleostean species. Hatching occurred between 17 and 18 days after spawning at a mean water temperature of 8.5&deg;C. The newly hatched larvae averaged 4.44 mm in body length (BL). The larvae attained to post-larval stage at 5.80 mm BL, and juvenile stage at 10.2 mm BL. A specific feature of the post-larvae was the appearance of three lines of the melanophores on the caudal part of fin fold. Carotenoid first appeared on the nape at 8.70 mm BL, heavily emerged beyond 12.9 mm BL, and turned up on the back also beyond 15.2 mm BL. Scales on the lateral line were completed by 18.5 mm BL. Three pairs of flaps were observed on the dorsal surface of the head at 37.0 mm BL. External features of adult specimens are almost completed by 52.0 mm BL, yet the tip of the first preopercular was not branched but remained simple.
  • H MUNEHARA, S MISHIMA  JAPANESE JOURNAL OF ICHTHYOLOGY  33-  (1)  46  -50  1986/05  [Not refereed][Not invited]
     
    The eggs of Alcichthys alcicornis were spawned in tank at the laboratory and reared for the studies of embryonic, larval and juvenile development. This species takes place entosomatic fertilization, and females spawn fertilized eggs after copulation. The eggs are demersal and adhesive, released as a clump forming a thin layer on the bottom of tank. There was no significant difference in embryonic development between this species and other oviparous teleostean species. Hatching occurred between 17 and 18 days after spawning at a mean water temperature of 8.5†C. The newly hatched larvae averaged 4.44 mm in body length (BL). The larvae attained to post-larval stage at 5.80 mm BL, and juvenile stage at 10.2 mm BL. A specific feature of the post-larvae was the appearance of three lines of the melanophores on the caudal part of fin fold. Carotenoid first appeared on the nape at 8.70 mm BL, heavily emerged beyond 12.9 mm BL, and turned up on the back also beyond 15.2 mm BL. Scales on the lateral line were completed by 18.5 mm BL. Three pairs of flaps were observed on the dorsal surface of the head at 37.0 mm BL. External features of adult specimens are almost completed by 52.0 mm BL, yet the tip of the first preopercular was not branched but remained simple. © 1986 The Ichthyological Society of Japan.

Research Grants & Projects

  • 半クローン雑種の総括研究-永続性の実証(究極要因)とゲノム削除機構(至近要因)
    日本学術振興会:科学研究費助成事業 基盤研究(C)
    Date (from‐to) : 2021/04 -2024/03 
    Author : 宗原 弘幸, 藤本 貴史
     
    半クローンやクローンは、雌だけを産むため個体群増殖速度が速いが、遺伝的な多様性を作り出せないなどの欠点から、系統寿命は短いと考えられてきた。しかし、アイナメ属半クローン雑種を用いた研究から、一世代で父親ゲノムを「置換」できる半クローンの特性により、母種の雄と交配することで組換え可能な子を作り出せる。本研究では、アイナメ属の系統進化の過程で、ホスト種を換えることによって半クローンと組換え世代を繰り返し、系統寿命を伸ばしてきたことを実証する。さらに半クローン配偶子が形成過程を細胞学的に解明する。 本年度は以下のことを実施した。 1. 父種ゲノムの削除機構の細胞学的観察と遺伝マーカーの作成 半クローンは、体細胞では父種と母種のゲノムが協働して雑種成体となるが、生殖細胞は母種ゲノムだけを伝える配偶子を作る。父種ゲノムが排除される仕組みを明らかにするため、卵原細胞から卵母細胞になるまでの染色体動態を蛍光観察するためのプローブ作成を行った。 2. 半クローン遺伝子のホストスイッチを経由した永続性の実証 スジアイナメゲノムの半クローン雑種には、アイナメを宿主にするアイナメ系とクジメを宿主にするクジメ系が北海道南部とロシア沿海州で見つかっている。スジアイナメは北太平洋東岸で起源し極東まで分布を広げた。その過程には、多様な環境があったが、そこを近縁種のゲノムを宿主にして乗り越えて極東にたどり着いたと考えられる。これを『ホストスイッチ仮定』とよんでいる。これを実証するために、もっとも寒冷域にまで分布するエゾアイナメを厚岸町から入手した。エゾアイナメの精子で半クローンの卵を人工受精した。その結果、受精し、孵化仔魚も他の純粋種と比較して順調に育つことがわかった。本年度は得られた稚魚のDNA量、両親種のゲノムが遺伝したことを確認した。次年度はこの雑種が半クローンかどうかを確認する。
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2017/04 -2020/03 
    Author : MUNEHARA Hiroyuki
     
    Unisexual vertebrates (i.e., those produced through clonal or hemiclonal reproduction) are typically incapable of purging deleterious mutations, and as a result, are considered short-lived in evolutionary terms although high increasing rate. However, most of clonal and hemiclonal vertebrates have existed far longer than expected theoretical generation longevities. This study clarified that hemiclonal Hexagrammos hybrids use two-way backcrossing (clonal genomes are returned to the gene pool where they can undergo recombination plays an important role in increasing the genetic variability of the hemiclonal genome and reducing the extinction risk). In this way, hemiclonal lineages may have survived longer than predicted through occasional recombinant generation. In addition, genes inducing hemiclonal reproduction by discarding of paternal genome during oogenesis have been identified by RNA-seq although not yet being completely analyzed.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2016/04 -2019/03 
    Author : Awata Satoshi
     
    Marine sculpins (Cottidae) exhibit diverse reproductive modes and parental behaviors within a family: non-copulatory- and copulatory species with male care, copulatory species with female care and copulatory species with ostracophils. Here, the effects of reproductive modes and the mode of parental care on the evolution of sperm traits (sperm morphology and motility), male genitalia and ovipositor were investigated in 37 sculpin species. (1) We show that sperm traits and male genitalia may have evolved driven by environmental factors independent of the phylogeny in this group. This may be the first report showing the evolution of sperm depending on the copulatory behavior and sperm competition among animals. (2) We also show that ovipositor length and morphology in ostracophilous sculpins could change owing to the host species used (tunicates or sponges) and their size, even among conspecific populations of marine fish with presumably low dispersal ability.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2015/04 -2019/03 
    Author : ARAI KATSUTOSHI, DENBOH takashi, TAKAHASHI eisuke, ENDOH mitsuru, KURODA masamichi, SHIMA fumika, SHIBATA kiko, SUZUKI shota, CIERESZKO andrzej, DIETRICH mariola, NYNCA joanna
     
    Hybridization between different fish species produced viable or inviable progeny. Recovery of survival potential by allotriploidization was often recorded in certain inviable hybrids. In viable hybrids, germ cells were not normally differentiated and hermaphroditic gonads were frequently detected. Natural clonal loach has the hybrid origin between two genetically diverse strains. Each chromosome of the clone cannot find its counterpart for pairing in the course of meiosis. Thus, each chromosome is duplicated by premeiotic endomitosis and then sister chromosome pairing assures the formation of isogenic gametes. Natural Hexagrammos hybrids have large metacentic chromosomes closely linking to hemi-clonal reproduction (hybridogenesis). Thus, these chromosomes were used as marker of hemi-clone to detect presence or absence of back-crossed progeny between hemi-clonal hybrid female and paternal pure species.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2014/04 -2017/03 
    Author : Munehara Hiroyuki
     
    Global climate changes will alter many local fauna and flora, especially inhabiting high latitude boreal area. Changes of fish fauna along Hokkaido and sequences of the secondary contact between two close Hexagramids species were investigated genetic ecologically. As a result, the first records of 9 species including the Northernmost records of 6 species were found from specimens collected with SCUBA Diving from Southern Hokkaido. This finding suggests that at the present, fish fauna in Hokkaido is changing to more temperate-zone type. The secondary contact between Hexagramids species produced hemi-clonal hybrids. Hemi-clonal genome can migrate hemi-clonal hybrid population and their maternal species population by "host-switching", is referred to as changes in the species of the sperm donor among hybrids employing (hemi-) clonal reproduction. Including this example of the secondary contact without genetic penetration, this study clarified a part of diversities by species contacts.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2013/04 -2016/03 
    Author : MUNEHARA Hiroyuki, YABE Mamoru, KOYA Yasunori, AWATA Satoshi, ABE Takuzou
     
    Sampling of Cottoids (Cottidae, Rhamphocottidae, Psychrolutidae, Agonidae, Cyclopteryidae, Hexagrammidae) using with SCUBA diving was conducted at Kamchatka Islands, Unalaska and Vancouver, and sampling by trawl net from University training ship also done in the Arctic Ocean. We successfully collected about 50 species from precise species identification after research. We carried out a molecular phylogenetic analysis from 6 families 47 genera 92 species including specimens collected in this study. As results we proposed some hypotheses such as species divergences from offshore to coastal area, disruptive evolution of species distributing in the East Pacific and the West Pacific and large phylogenetic vertical migration by lacking bladder. We also investigated the evolutional process of invasion to the Arctic Ocean by cottid fishes from genetic analyses of antifreeze proteins.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2011/04 -2014/03 
    Author : MUNEHARA HIROYUKI, ARAI Katsutoshi, AWATA Satoshi, HAYAKAWA Youichi
     
    Hexagrammos populations including the hemi-clone strains were analyzed with genetic markers. Ecological researches and artificial closs breeding suggested that hemiclonal strains were different from F1 hybrids between pure species and possess certain genetic materials to hemi-clonally reproduce. In addition one or two sets of chromosomes of hemi-clonal strains fused as the Robertson translocation. The clossbreeding experiments suggested that the translocation may be inducing factors of hemiclone reproduction. A hypothesis concerning the longevity of hemiclonal strains was proposed based on these findings. Hemiclone hybrids usually mate with males of paternal ancestors, but the hybrid would possess the same genome composition as the hemiclone origin species if the hybrids mate with males of maternal ancestors. This type produces recombined gametes, so hemiclonal genome can produce renewal genetical diversity. Thus, the longevity of hemiclonal reproduction will be guaranteed.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2010 -2012 
    Author : KOHDA Masanori, MUNUHARA Hiroyuki, MATSUMOTO Kazunori, HATA Hiroki
     
    We studied social structure and reproductive strategy of cichlids of Lake Tangnayika, especially cooperative breeding species, indicate following major suggestions or conclusions. Neolamprologus obscurusconduct cooperative breeding with related helpers, a
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2009 -2012 
    Author : KINOSHITA Izumi, SAKAI Harumi, MUNEHARA Hiroyuki, TAKAHASHI Hiroshi, GOTO Akira, YOKOYAMA Ryota, MABUCHI Kohji
     
    Of 33 spp. from 12 gen., three fam. in the Baikal sculpins, 27 species were inferred by analysis of mtDNA and ncDNA sequence data, and each genus showsmonophyletic group and forms a phylogenetic tree of reliable relationship. Furthermore, the deep-water sculpins could be one of ancestors for group distributed around the Arctic Zone, and the process of their adptive radiation was clarified. Larvae of pelagic sculpins had been distributed in layer deeper 100 m offshore and at surface nearshore in Comephorus and Cottocomephorus, respectively. Two genus hardly showed vertical diel migration. Based on their results, sympsium: “Origin, adaptive radiation and speciation of sculpins in Lake Baikal” with 10 papers was convined in September.
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2007 -2008 
    Author : MUNEHARA Hiroyuki
     
    交尾は、肺呼吸、四足歩行と並んで、ヒトを含む脊椎動物が陸圏に進出する際の前適応である。交尾の進化過程を再現するため、近縁種に交尾種と非交尾種を含んだカジカ上科魚類をモデルとして、雄間の競争、特に精子競争の影響に焦点を当てて、実験的に調査した。行動形質の評価指標として繁殖成功度に注目した。その結果、射出精子量、交尾の順番が、繁殖成功度に影響し、先にたくさんの精子を雌に渡すという行為が交尾の進化動因であることが示唆された
  • A study of reproductive ecology of Lake Tanganyikan cichlid fishes as the model systems of cooperative breeding in vertebrates
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2005 -2007 
    Author : KOHDA Masanori, NAKASHIMA Yasuhiro, MUNEHARA Hiroyuki, KARINO Kenji, WATANABE Katsutoshi
     
    In the last year, Drs. S. Awata, K Ota and S Morita conducted field observations. In this year, the cooperative breeding cichlid fish, Julidochromis ornatus is mainly studied. As the studies during the three years, it will be newly confirmed that (1) within a population this fish has most varieties of mating systems, e. g., monogamy, polygyny, classical polyandry, cooperartive polyandry, and polygynandry. This variety will be most in vertebrates, and has been reported from the acorn woodpecker. (2) These variations will be induced by the largest females that can dominate over males. Thus, these females physically control or manipulate males. Thus, not only the sperm competition and a variation of social mating systems, this fish will be good subject animals for the study of female control of paternity, deception, intra- and inter-sexual confficts, reciprocal altruism and mutualism, all being the interesting themes for future research in behavioral ecology. Thus, we are going to make experimental studied in laboratory using this species during the future 5-10 years. Another cooperative breeding cichlids Chalinochromis brichardi has been studied also in this year. This fish was studied for ca,. 10 years. The mating systems of this fish consist of monogamy, cooperative polyandry and polygynandry. This variation in mating system is smaller than that of J. ornatus partly because that female size was smaller than large alpha males. Thus socially most dominant individuals were males. Thus, dominant order resemble that of the bird dunnock, in which most dominant individuals are alpha males and the cichlid breeding systems also resemble that of the dunnock where cooperative polyandry, monogamy, polygynandry are predominant. Thus, it will be shown that in cichlid fishes of cooperative breeding degree of variations in mating systems are different between species. In Telmatochrmis vittatus, it has been observed that this study population consisted of multiple male reproductively parasitic male-mating tactics: sneaking tactics, satellite-male tactics and pirate male tactics. We hypothesized that sneaker males can evolve to beta males, if they become to conduct paternal care after fertilization, and pirate males can be alpha males, if they target monogamous breeding pair (where pair males to be beta males with parental care). DNA phylogeny analyses may suggest that the genera Telmatochromis, Julidochromis and Chalinochromis will be closely related (but some reports do not support this). If this will be the case, we may say that the alternative male reproductive tactics will have the same root in their origin species. Additionally speaking, the alternative male reproductive tactics in species of these three genera are not genetically determined but changeable according to their growth.
  • Evolutionary and ecological studies on the circum-north Pacific elements, the super-family cottoid
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2005 -2007 
    Author : MUNEHARA Hiroyuki, YABE Mamoru, KOYA Yasunori, HAYAKAWA Youichi
     
    To verify the polyphyletic evolution hypothesis of copulating within cottoid, we had the researches to collection of fish samples for investigation of molecular phylogeny including the western Pacific species and the fine structural morphology of the reproductive tract on cottoid species. We collected 5 families 60 species 1500 specimens during three expeditions, the Puget sounds and Vancuver in March 2006, Unalaska island in July 2006, and Peter the Great Bay in November 2007. Process of gonadal sex differentiation and formation of reproductive organ were investigated in uncopulative sculpin Cottus. In Cottus, the differences in morphology of urogenital projection between male and female appeared considerably late period after having completed gonadal sex differentiation. Remarkable specialization was admitted in the morphology of testis and sperm among Cottidae. Especially, some common characteristics (slender sperm head, eosin positive-secretion, sperm bunch, asynchronous spermatogenesis) were observed overcoming genus in copulative sculpins. It is thought that each characteristic is an adaptation to the copulation related to the spermatogenesis and the sperm motility. We investigated the differentiation of germ cells toward normal fertile sperm (eusperm) and non-fertile dimorphic sperm (parasperm) by using Hemilepidotus gilberti. We obtained eusperm and parasperm by cell culture of germ cells from spermatocytes collected from teites, indicating DNA-duplicating spermatocytes are potent to autonomously progress a part of spermatogenesis to form parasperm. By electrophoretic analysis of acid extracts from eusperm and parasperm, specific protein bands for each type were detected in its electrophoretic patterns, indicating the condensation of nucleus of the different type of sperm occur through a different sperm-specific nuclear basic proteins.
  • Ecological Studies on Crossbreeding among Hexagrammos Species
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2004 -2006 
    Author : MUNEHARA Hiroyuki, YABE Mamoru, IMAMURA Hisashi, HAYAKAWA Youichi
     
    In hexagramids, one boreal species (Hexagrammos octogrammus) and two temperate species (H.otakii and H.agrammus) are distributed in the coast of Japan, and crossbreeding among the three species is known to occur. This study was conducted to clarify what ecological factors involve in the crossbreeding. 1.The preference of spawning substratum differed among the three species. In natural habitats, H.otakii occurred deeper than the other two species which preferred to seaweed. On the other hand, the three species established concurrently their breeding territory in the artificial area. 2.H.octogrammus females were observed in the spawning area of H.otakii on breaker zone, and hybrids were often observed near the artificial fish reefs. It was possible to discriminate visually the eggs of H.otakii from the other two species because of difference of egg-coloration. Several egg masses of H.octogrammus or H.agrammus were often deposited in the H.otakii terrirories. 3.Polymorphism of mtDNA enables to discriminate what species deposited the egg masses in the territory of H.otakii. 40% of the egg masses deposited in H.otakii territories was crossbreeding, and mother of all of them was H.octogrammus. 1.9% of the egg masses in H.agrammus territories were deposited by H.octogrammus. No eggs of H.otakii were observed in the other species territory. This uni-direction hybridization showed that gene introgression from H.octogrammus into H.otakii is proceeding through crossbreeding. 4.80 individuals of hybrid and backcross were collected during this study. Sex of all the fishes was female. To clarify this sexual bias FISH method and survival experiments of embryos were conducted. FISH method denied a possible of gynogenesis of hybrid, and there was no significant difference the survival rates of between purebred embryos and crossbred ones. These results suggested that genetic males exist at least just after hatching.
  • A study on reproductive tactics in four species of cichlid fishes: model systems of cooperative breeding in vertebrates
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2004 -2006 
    Author : KOHDA Masanori, MUNEHARA Hiroyuki, WATANABE Katsutoshi
     
    During the three years of this project, we have consistently conducted laboratory experiments using the cooperatively polyandrous cichlid, Julidochromis transcriptus. Main studies of this projects are three : (1) The effect of body size on mating systems and parental roles in J. transcriptus, (2) Sperm competition between alpha and beta males in a cooperative polyandrous trio in J. transcriptus and (3) Female control of paternity in cooperative polyandrous trios in J. transcriptus. In he last year, we conducted laboratory experiment on the second and third themes. The results of these experiment may have a strong impact. To test the female control hypothesis, we conducted aquarium experiments. Both alpha and beta males of this cichlid jointly take care of broods. Alpha males are aggressive against beta males during spawning, where they are in strong sperm competition. We created breeding pairs (female with alpha or beta male) and trios (female with both males) in various experiments. In the first experiment we tested whether females in pairs or in trios prefer wedge-shaped sites for spawning (experiment la, Fig. la). The hypothesis tested is that females only prefer wedge-shaped nests in trios (i. e. to allow beta males access to spawning and induce beta male care). Then, to verify the significance of using wedge-shaped sites, only an open (non-wedge) nest was given to trios and their nest usage was observed. In the second experiment we examined the reproductive behavior of females in trios, and compared them to females paired only with an alpha male or a beta male. As expected, in experiment la, our first experiments show that females of J. transcriptus in trios prefer to use the wedge-shaped sites, which allow both beta and alpha males to enter the nest site and participate in spawning. The second prediction is that wedge-shaped nests allowed females to divide the paternity amongst multiple males. Beta males are expected to fertilise the eggs laid in the inner-part of the wedge, alpha males in the outer-part of wedge, and thus the paternity distribution will change according to the egg and clutch position in the wedge-shaped sites. As predicted, eggs in the frontal, wider part of the clutches were predominantly sired by the alpha males, whereas the beta males sired more offspring in the back, narrower part of the clutches. Similarly, the proportion of offspring sired by beta males increased when eggs were deposited at the more inner part of the wedge. Females appear to manipulate the likelihood of both males gaining paternity by choosing the position of the clutch inside the wedge carefully. The third prediction is that shared paternity increases the brood care performed by the males, and it reduces female brood care. Neither alpha nor beta male showed an increase in brood care behavior with siring success. However, females had a lot to gain from inducing beta male brood care: (1) in trios, beta males performed more brood care than alpha males. (2) Beta males in pairs (where they have full paternity) provided more brood care than beta males in trios. (3) Alpha males in pairs tended to provide less brood care compared to alpha males in trios. Thus, total male brood care in trios was much larger than brood care by alpha males in pairs, but was not different from brood care by beta males in pairs. Consequently, females in trios provided less brood care than females paired with only alpha males, but was similar to females paired only to a beta male. We conclude that females may reduce their share in brood care by attracting a beta male care-giver to the brood, which will be more likely to succeed when she selects wedge-shaped nest sites. This strongly suggests that female nest choice in J. transcriptus is strategic and relates directly to attracting both potential care-givers to her nest. We have shown that experimental studies of female control of group membership and paternity are needed to gain a deeper understanding of vertebrate cooperative breeding systems, as it may affect e. g. reproductive skew, sexual conflicts and mating systems.
  • スキューバ潜水による着底稚魚の効率的採集機材の開発
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Exploratory Research
    Date (from‐to) : 2004 -2005 
    Author : 宗原 弘幸, 三浦 汀介, 矢部 衛
     
    本年度は、昨年度作成した水中スクーターを装着したそりネットを使って、毎月1〜2回の試験操業を行い、試作機の性能評価と臼尻実験所前浜の着的稚魚相の季節的変化を調査した。結果は以下の通りである。 操業 1.採集地まで磯舟で向かい、ダイバーが2台の水中スクーターを持って潜行する。その後船上からソリネットを沈める。スクーター、フローメーターおよび水中ビデオをソリネットに装着し、10分間海底を標本調査した。曳網速度は時速3km以上で、ヒトデなど抵抗が大きい生物の大量入網でも時速2kmを維持できた。操業後スクーターなどをはずし、ロープでネットを船上まで引き上げ、ダイバーもスクーターなどを持ち浮上した。この操業を毎回2箇所で行った。 2.操作性は、当初のコンセプトを満足できるものであった。ネットフレームの強度上、水中スクーターなどの取り付け取り外しを水中で行うが、この時間の短縮が課題であった。かなりの部分をワンタッチにし、最終的には当初の半分の3分程度でできるようになった。 標本調査 1.4月から1月までの間に11回の調査を行い、約35種500個体以上の着底稚魚が採集された。その中には、臼尻実験所初記録で北限記録を更新したアラメガレイ、セトヌメリなども含まれている。魚類以外でも様々な無脊椎動物の季節的な出現パターンを明らかにすることができた。 2.水中ビデオの映像から、体長30mm以下の魚類であれば、網からの脱出はないと推定された。ただし、砂底域は波状になっており、埋在生物だけでなく表在生物にもキャッチミスがあると考えられた。今後は、網口の改良により、CPUEではなく、単位面積での絶対値比較が可能になることを目指す。また、今回、水深が同じで環境が若干異なる2地点を調査地点として実施したが、それでも採集結果にかなりの違いが認められたため、多数の採集地を設けることで、より詳細な着底稚魚研究が進展できることが示唆された。
  • Study of reproductive ecology and sociality of Lake Tanganyika cichlids : a model system of social evolution of vertebrates
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2002 -2004 
    Author : KOHDA Masanori, NAKASHIMA Yasuhiro, MUNEHARA Hiroyuki, KARINO Kenji
     
    In this year, Kohda and Takeyarna as a cooperator studied in Lake Tanganyika. Kohda researched breeding ecology of cooperatively polyandrous cichlid Chalinochramis brichardi, especially on the spawning sites in wedge-shaped nests. He found further examples where egg clutches were deposited at the point in the nest to which large alpha males can reach. These were similar to depositing sites observed in previous years. These results may indicate female selectively spawn eggs at the site to which large alpha males can reach, and may lead the hypothesis that through selection of spawning sites by females of this fish, they may control paternity distribution in this fish. In laboratory experiments at the Mpulungu City, female choice of nest shape, wedge-shaped nests and wide nests was examined. AS predidted from field observation in previous years, female tended to choose wedge-shaped nests in which female can control paternity distribution. From field observation of C.brichardi, we obtained further examples of egg clutches. Of 11 egg olutches 10 were deposited at the site in nest to which a large alpha male can enter. We made a hypothesis that females can control paternity distribution by selecting such sita as spawning site. Female control of paternity distribution in cooperative breeding vertebrates has been suggested, The test of this hypothesis will be the first example of female control of paternity distribution in extra-fertilizing animals. N.savoryi is known as a haremic cichlid. We found that this fish has helpers, probably related. Cooperative breeding with related helpers has been reported in birds as well as cichlids, but both in birds and cichlids breeding members are of pairs. Thus ; the cooperative breeding of N.savoryi will the first example in haremio mating system. We will examine the relatedness between adults and helpers using samples. We brought ca. 40 individuals of N.savoryi to the laboratory of Osaka City University. Using these live fish, we will conduct aquarium experiment on the cooperative breeding of this fish,
  • Study on social and ecological factors promoting cooperative polyandry in fish and on their reproductive tactics
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2001 -2003 
    Author : KOHDA Masanori, MUHEHARA Hiroyuki
     
    Male investment to testes, female control of paternity distribution between territorial males and helper males, and effect of fish body size in cooperatively breeding cichlid fish Julidochromis transcriptus were studied in laboratory conditions during 2001 and 2004. In this cooperatively polyandrous fish, it was cleared that both two males in polyandry invested in testes size significantly much more than males in monogamous situation where sperm competition should not exist. Moreover, the polyandrous males have already increased the testes size after one month of the start of experiment, suggesting they can immediately change the degree of investment This is the first document that individual males can dynamically change testes investment according with the intensity of sperm competition. Female control of paternity distribution was confirmed by using designated artificial nests In this case, results obtained from experimental fish of cooperative breeding (trio) were compared with those of paired fish. Female with territorial pair male and small helper males spawned egg masses in wider ranges than paired females. DNA analysis of eggs revealed that 1) eggs of polyandrous females were sired by both males, 2) eggs in inner side of nest were sired by small helper males and those in outside of the masses were sired by large pair males. This tendency suggests that potyandryous female spawned eggs in wider range to fertilize the egg by both males. The manipulation of egg depositing site by females may provide the chance of female control of paternity distribution between the two males. When small males sired more number of eggs, they tended to provide more paternal care. This implies that the female afford to obtain more paternal care through her control of paternity, as has been indicated in cooperative polyandrous bird, the dunnocks. This study will be the first that provide evidence of female control of paternity in fish. Our field studies on the mating system of J.ornateus, the congeneric species to J.trascriptus revealed that the former has a variety of mating systems, monogomay, cooperative polyandry and haremic polygamy. It is suggested that the main ecological factor inducing the variation is wide size variation in both sexes. We tested the hypothesis, using J.trascriptus of 3 males and 3 females in the same experimental aquaria. When size of all fish were similar monogomay was predominant. When one male was much larger than others, polygyny was formed in all cases. When a female was dominantly larger, polyandry was made. These results should support the hypothesis. Chalinochrormis brichardi has cooperative polyandrous mating system, in which female control of shared paternity has been suggested. For the control females should obtain wedge shaped nest where small beta males can seek refuge from dominant alpha males. Our preliminary experiment I on female choice of two nests of wedge-shape nest and wide nest which do not have such refuge indicated that the female choose wedge-shaped nests. The results implies that female control may be the case in C.brichard. Cooperative breedings have been documented in birds and mammals. A number of model of reproductive skew have been proposed for understanding of the breeding systems. Recently, members of our research team have revealed that in fish cooperative breeding with unrelated helpers, 1) helpers (beta males) share the paternity, and 2) helper numbers are restricted, one in C.brichard. These are consistent with the prediction from reproductive skew models. However, mechanism of paternity share between two or more unrelated males has not been cleared in these models. Our experimental studies suggest the importance of female control of paternity, which should be paid much more attention.
  • Studies on the diversity and creative mechanism of the reproductive mode in copulating teleost fishes
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2001 -2002 
    Author : MUNEHARA Hiroyuki
     
    The present studies carried out a ecological and physiological examination on Scorpaeniformes cottoid species, with the focus of the spawning mode and functional morphology of testes as out-adaptive traits for evolution of copulating behavior. 1. Histological observation for investigation of on ovarian annual cycle showed that Radulinopsis taranetzi and R. darjevini, maternal care and copulating fishes, are potential multi-spawners. Experimentally, females of these species spawn two times in a breeding season only when the egg masses was taken out of aquarium tank before hatching, but both spawned only one time when the females succeefully protected the first egg mass until hatching. These results suggested that the second clutch of these cottids is for compensatory eggs when the first clutch was eaten during developing. 2. Histological observation on testes showed that copulating period and sperm strage system in testicular organ differed between R. taranetzi and R. darjevini. R. taranetzi copulates for six months from January to July, while R. darjevini for ten months from September to July. In the latter fish, testis weight is relatively heavier and sperm is stored more compactly as sperm bunch than those of the former. In addition small chamber, which is enclosed with connective tissues, is provided near the opening of the tip of penis. It is plausible that these morphological differences function to emit much sperm into female genital tract for intensive sperm competion (long copulaing period). 3. A non-copulating sculpin, Hemilepidotus gilberti, produce much apyrene spermatozoa with plural nuclei during spermatogenesis. The function of apyrene sperm were investigated with fluorescent dye and microsatellite DNA polymorphism. It was showed that the sperm played as a broker toward sneaker's eusperm for sperm-competition. In addition it is experimentally showed that apyrene spermatozoa have antidispersive function. 4. The past studies indicated that copulating cottoids are multispawers while non-copulating cottoids are single spawner. Multi-spawning brought much benefit for copulating individuals but not benefitial for non-copulating fishes. The present study investigated for Radulinopsis species, showed that the above concept may not adaptive for at least maternal care and copulating fishes.
  • Studies on the reproductive ecology of littoral animals using with DNA polymorphism
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 1998 -2000 
    Author : MUNEHARA Hiroyuki
     
    The present study clarified about the reproductive ecology of some littoral animals as follows. 1. Interspecific breedings among three hexagramids were observed with underwater video camera and mtDNA and genomic DNA (calmosurin encording region) polymorphism analyses. The cross breedings did not occurred at random, but only two combination, between male Hexagrammos otakii and female H.octogrammus and between male H.agrammus and female H.octogrammus. All hybrids were female. DNA analyses detected F2 individuals, suggesting F1 hybrids are fertile. 2. Primers of amplification of microsatellite DNA polymorphism were designed for paternity determination of Hypopthychus dybowskii. Males of this fish established a spawning territory around sargassum sea wedows. Five primers successfully amplified microsatellite DNA loci. Of them 4 sets of the primers showed high heterooccurrence frequency of 80% over. Relationship among density of fishes, density of spawning substratum and reproductive success is being investigated with the DNA polymorphism. 3. A non-copulating sculpin, Hemilepidotus gilberti, produce much apyrene spermatozoa with plural nuclei during spermatogenesis. The function of apyrene sperm were investigated with fluorescent dye and microsatellite DNA polymorphism. It was showed that the sperm played as a broker toward sneaker's eusperm for sperm-competition. 4. Primers of amplification of microsatellite DNA polymorphism were designed for cichlids in Lake Tanganyika, Telmatochromis temporalis and Julidochormis ornatus. The analyses resulted that the two species have a unique mating system, helpers and pirates sired with some of guarded eggs by pair.
  • 魚類における温度依存性決定機構の生態的意義
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Exploratory Research
    Date (from‐to) : 1998 -1998 
    Author : 島崎 健二, 成松 庸二, 宗原 弘幸
     
    は虫類、両生類で広く知られている温度依存性決定(TSD)について、魚類でのその適応的意義を、シワイカナゴについて調査した。この魚種は春季の昇温期に繁殖することと、寿命が一年であることから、生活史を通じたTSDの適応的意義に関する研究モデルに適当と考えられた。性決定感受期および軸水温を飼育実験から、胚期から繁殖期までの生残、成長、繁殖成功度における産出日と雌雄差を野外調査と耳石日周輪紋の計数より、それぞれ明らかにした。その結果、稚魚期までのほとんどの個体は死亡するが、生き残った個体については、産出日が産卵期の中頃に産まれた個体で生残率が高かった。成魚については、水槽内の飼育実験から、早く産まれた個体ほど大型となる傾向が認められ、雌では産卵数が多くなるため、産出日と繁殖成功度の相関が示唆された。一方、雄では体サイズとつがう雌の数に相関が認められなかったことから、産出日と繁殖成功度に相関がないとみなされた。成魚の体サイズ(産出日=環境水温)と雌雄の繁殖成功度の比較からは、水温が低い繁殖初期では雌となり、水温が上昇する繁殖後期では雄となるのが有利に見えた。しかし、生活史全体で比較すると、本種のように稚魚期までに100%近く死亡し、体サイズを介して温度依存的な性決定の有利性が繁殖期のみにしか現れない場合、TSDが進化しにくいことが予想される。これがは虫類や両生類に比べ、魚類でTSDがあまりみられない理由と考えられるが、この点については、さらに現在、飼育実験結果をもとに解析中である。
  • Survey for resource estimation of substrate spawning littoral fishes with using underwater video camera system
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 1996 -1997 
    Author : MUNEHARA Hiroyuki
     
    1.The reproductive behavior of Hexagrammos otakii, H.octogrammus and H.agrammus was observed using an underwater video camera system and SCUBA diving. The following results were chiefly obtained. (1) The reproductive behavior of the 3 species was generally similar, so interspecific crossbreeding, in which female H.octogrammus responded to the courtship of male H.otakii. There is a possibility that concrete blocks of a quay loosen the native reproductive isolation. (2) Sneaking followed pair spawning is 11 of the 26 spawnings. Paternity discrimination for 2 egg masses using microsatellite DNA suggested that 84% of all the eggs deposited in the nest were kin to the territorial male, and the remaining 16% were sired by sneakers. 2.It was examined which factor influenced to survivorship of the early life stages of a parental care fish, Hypoptychus dybowskii. Earlier spawned eggs underwent higher mortality during embryonic stages. The cause was predation by fishes such as hexagramids based on the observation with SCUBA diving. Analyzes on otolith daily increments suggested that earlier spawned individuals also underwent higher mortality during larval stages. However, earlier spawned individuals could gain larger body size upto adult stage. Survivorship during embryonic stages to spawning state required for seaweed forests. 3.The reproductive cycles of hair crab and helmet crab were examined by using the histological observation. These 2 crabs have the similar reproductive cycle, in which consist of oocyte growth, spawning, incubating, molting, and copulating. One cycle of hair crab take at least 2 or 3 years, but that of helmet crab does one year. Females stay under sandy bottom during long incubation period because of defenseless. Exhaustive protest of incubating females is important to reserve the crab resource.
  • 沿岸性魚類の卵保護習性に関する資源生態学的研究
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Encouragement of Young Scientists (A)
    Date (from‐to) : 1995 -1995 
    Author : 宗原 弘幸
     
    1.設置型水中カメラによる行動観察とDNA分析による血縁判定から、アイナメ類とカジカ類の繁殖生態を調査した。 2.アイナメとスジアイナメ、いずれもスニ-キングが観察された。しかし、アイナメでは、スニーカーは若齢の非なわばり雄であったのに対して、スジアイナメでは、隣接するなわばり雄であった。スジアイナメの繁殖地では、高密度で繁殖なわばりが形成されることが関係していると判断された。また、DNA解析から、いずれのスニーカーも、子どもを残していることが確かめられた。 3.アイナメでは、保護雄が自分の産んだ卵に対する捕食が観察された。捕食は卵の基質への接着がゆるみ脱落した際に生じた。捕食された卵はスニ-クされた卵塊であることが多かったが、スニ-クの際に雄同士の争いで接着が不十分になるように思われ、なわばり雄が血縁の信頼性の薄い卵塊を選別して捕食しているとは、結論できなかった。 4.以上の調査結果から、繁殖に適した場所が不足すると、なわばりが高密度で形成され、スニ-キングが頻繁に起きるようになる。そのため、ふ化前に基質から脱落する卵塊が増え、個体群が減少する仕組みの存在が示唆された。したがって、沿岸域に多い基質性産卵魚の増殖にあたっては、種苗放流だけでなく、繁殖場の整備がきわめて重要であろう。 5.イソバテングとケムシカジカの卵を、カイメンなどの無脊椎動物から見いだしていたが、今回の観察から雌が単独でそれらの生物に産卵することが分かり、これらのカジカ類は産卵前に交尾をすることが明らかとなった。
  • カジカ科魚類における交尾の成立基盤
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Encouragement of Young Scientists (A)
    Date (from‐to) : 1993 -1993 
    Author : 宗原 弘幸
     
    行動観察、受精生理および遺伝学的手法により、本課題を遂行した。その結果、ヨコスジカジカは産卵後に雄が卵に放精する、非交尾種であることが判明した。しかし、精子の運動活性は海水中よりも体液と等張でNa^+存在下で最も高く、特に卵巣腔液中では極めて長期間活動する。媒精、受精は産卵時に放出される卵巣腔液中であることから、非交尾カジカはすでに交尾への準備が進んでいることが示唆された。また、卵巣腔液中で受精可能な点は体内配偶子会合型の交尾種と相違した。その要因は卵巣腔液中のCa^<++>濃度の違いで、カジカ類では交尾習性の進化の際に、卵巣腔液中のCa^<++>濃度を下げる生理的メカニズムの変化があったことが示唆された。卵巣腔液の役割として精子の貯留や活性保持の他に、ケムシカジカでは交尾の際の精子受け渡しの媒介となることが水槽内観察より明らかになった。本種の交尾行動は、一連の求愛儀式を経た後、雌の生殖口から管が出され、さらにそこからゼリー状卵巣腔液が放出され、そのゼリーの向かって放精されるというもので、精子が絡みついてゼリーの一部が再び雌の卵巣内に収納されることで交尾が完了する。ペニスがないカジカも交尾をするという、本行動観察結果は、カジカ科魚類にはかなり交尾をする種がいることを示唆した。交尾行動は繁殖生態の上で、父性のあいまいさをもたらす。特に雄が卵を守るニジカジカの場合、重要な問題である。そこでDNAフィンガープリントで、保護雄と卵の父性およびいつ交尾した雄が有利かを調べた。その結果、繁殖期の終期では雄と卵には父性がないこと、および最初に交尾した雄は多くの子を残せることが分かった。本研究結果は、卵の保護は雄にとって直接的な利益が無いことが示され、卵保護の進化に父性の信頼性は必ずしも平行しないこと場合があることが分かった。最後に、配偶子会合型、交尾種の地理的出現を調査する準備段階として、アラスカ産のカジカ類の繁殖期を把握する目的で、キナイ半島リサレクション湾の仔稚魚サンプルを調べ、春季に10種のカジカ科魚類が出現することが分かった。
  • カサゴ目魚類における生殖様式の進化 交尾型カジカの行動様式と受精について
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Encouragement of Young Scientists (Research Fellowship)
    Date (from‐to) : 1989 -1990 
    Author : 宗原 弘幸

Educational Activities

Teaching Experience

  • Special Lecture in Biosphere Science II
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : Aquatic Biology, Marine Ecology, Oceanography
  • Advanced Course in Aquatic Biology II
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 水圏動物、頭足類、スルメイカ、バイオロギング、バイオテレメトリー、海棲哺乳類、高次捕食者、生物多様性、生物地理要素 Aquatic animals, bio-logging, bio-telemetry, cephalopod, Japanese flying squid, marine mammals, top predators, selective breeding, biodiversity, biogeological elements
  • Field Training on Aquatic Biological Science
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 水産学部
    キーワード : 生物相・分類・生態・物質循環・行動・組織
  • Arts and Science Courses in English 2
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 国際本部
    キーワード : Ecosystem conservation, Sustainable bioproduction, Biodiversity, Material cycling, Harmonizable relation between human and environment
  • English Seminar
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 生態系保全、持続的生物生産、生物多様性、物質循環、人間環境共生系
  • Aquatic Ecology in the Northern Biosphere
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 水産学部
    キーワード : 高次捕食者、行動生態、遺伝マーカー、分子生態、バイオロギング


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