研究者データベース
Last Updated :2024/10/07
研究者情報
マスター
アカウント（マスター）
氏名
和田 哲(ワダ サトシ), ワダ サトシ
所属（マスター）
所属（マスター）
独自項目
syllabus
- 2021, 大学院共通授業科目（一般科目）：複合領域, Inter-Graduate School Classes(General Subject):Inter-Disciplinary Sciences, 修士課程, 大学院共通科目, データサイエンス，計算環境の再現性，計算環境の可搬性，推測統計，仮説検定，多変量解析，データ可視化
- 2021, 海洋生物学特論Ⅰ, Advanced Marine Biology and Biodiversity Ⅰ, 修士課程, 水産科学院, 統計解析、作図、統計解析フリーソフトR
- 2021, 海洋生物学特論Ⅱ, Advanced Marine Biology and Biodiversity Ⅱ, 修士課程, 水産科学院, 生活史、分布、生理、生態、行動生態、資源管理、種多様性、系統分類
- 2021, 水圏生物科学実習, Field Training on Aquatic Biological Science, 学士課程, 水産学部, 生物相・分類・生態・物質循環・行動・組織
- 2021, 水産科学英語Ⅱ, English for Fisheries Sciences II, 学士課程, 水産学部, 論文講読，科学英語，論文紹介
- 2021, 水産資源各論, Introduction of Fisheries Biology, 学士課程, 水産学部, 水産生物，分布，生活史，生態，漁獲方法，資源利用
- 2021, 海洋生物科学実験Ⅰ, Marine Science Biology I - Laboratory, 学士課程, 水産学部, 分析化学，環境分析，基礎?産，岩礁海岸の生物相
- 2021, 環境と人間, Environment and People, 学士課程, 全学教育, 海洋物理，海洋化学、海洋生態系，気候変化，プランクトン，ベントス，カレイ，サケ、深海魚、イカ・タコ類，鯨類，海鳥類，海獣類，衛星海洋学，人間活動，地球温暖化，海洋動物の保全・保護
- 2021, 実験統計学, Experimental Statistics, 学士課程, 水産学部, 記述統計，母集団推定，仮説検定、確率分布、相関，回帰，統計解析フリーソフトR
- 2021, ベントス学, Benthology, 学士課程, 水産学部, 底生動物、無脊椎動物、生態学、行動、生活史、自然淘汰、適応、資源配分、資源の選択、闘争、最適戦略、ゲーム理論
- 2021, 野外巡検, Field Observation, 学士課程, 水産学部, フィールド実習, 野外観察, 生物相, 生態学
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プロフィール情報
所属
学位
プロフィール情報
姓
和田, ワダ名
哲, サトシID各種
201301039098029391
対象リソース
所属
業績リスト
研究キーワード
研究分野
経歴
- 2016年04月 - 現在 北海道大学 大学院水産科学研究院 海洋生物資源科学部門 教授
- 2007年04月 - 2016年03月 北海道大学 水産科学研究院 准教授
- 2005年10月 - 2007年03月 北海道大学 水産科学研究院 助教授
- 2004年04月 - 2005年09月 熊本大学 沿岸域環境科学教育研究センター 助教授
- 2000年04月 - 2004年03月 高知大学 海洋生物教育研究センター 助教授
- 1998年04月 - 2000年03月 日本学術振興会 特別研究員 (PD)
委員歴
- 2013年04月 - 現在 日本ベントス学会 運営委員
- 2012年11月 - 現在 日本甲殻類学会 評議員
- 2010年04月 - 現在 日本ベントス学会 和文誌編集委員長
- 2008年04月 - 2010年03月 日本ベントス学会 和文誌編集委員
受賞
論文
- Haruto Gushiken, Satoshi WadaPlankton and Benthos Research 19 2 84 - 87 2024年05月31日 [査読有り][通常論文]
- Hiroyuki Yamada, Satoshi WadaEcological Research 2024年03月05日 [査読有り][通常論文]
Abstract Animal dispersal is often phenotype‐dependent and can exert evolutionary pressures on populations in which it occurs. The evolutionary pressure arising from phenotype‐dependent dispersal is called spatial sorting. We examined the evolutionary pressure arising from spatial sorting (sorting pressure) caused by downstream dispersal in juvenile white‐spotted char Salvelinus leucomaenis under ordinary flow conditions. We conducted outdoor experiments using an artificial channel with 10 steps to investigate the relationship between phenotypic characteristics and the occurrence or distance of downstream dispersal during five daytime hours. Six experiments were conducted using young‐of‐the‐year juveniles collected early in the morning of each experimental day. We focused on two phenotypes, fork length (body size) and station‐holding (SH) behavior, where juveniles remain sedentary on the substrate. Juveniles were assigned to the “SH group” if they exhibited SH behavior for more than 10 s during a 540‐s observation period, and to the “swimming group” if they exhibited SH behavior for less than 10 s. Juveniles in the swimming group had a higher occurrence of downstream dispersal than in the SH group. In addition, large juveniles in the SH group and small juveniles in the swimming group tended to show long dispersal distances. These results suggest an effective sorting pressure against juveniles with active swimming behavior. This sorting pressure may accumulate in isolated char populations located above a tall migration barrier and contribute to the creation and maintenance of the reported interpopulation variation in SH behavior. - Koichi Igarashi, Satoshi WadaJournal of the Marine Biological Association of the United Kingdom 104 e17 2024年03月 [査読有り][通常論文]
- Hiroyuki Yamada, Satoshi WadaJournal of Fish Biology 102 5 1168 - 1176 2023年03月13日 [査読有り][通常論文]
- Hiroyuki Yamada, Satoshi WadaJournal of Ethology 41 2 111 - 117 2023年01月10日 [査読有り][通常論文]
- Ryusei Yamakami, Satoshi WadaVenus 80 40 - 45 2022年 [査読有り][通常論文]
- Prey preferences of juvenile whelk Neptunea arthritica (Gastropoda: Buccinidae) in Hakodate Bay, Hokkaido, JapanRyusei Yamakami, Satoshi WadaPlankton and Benthos Research 16 257 - 265 2021年11月 [査読有り][通常論文]
- 北海道函館湾葛登支岬周辺の潮間帯に生息する巻貝相山上竜生, 和田哲北海道大学水産科学研究彙報 71 1 1 - 14 2021年08月 [査読無し][通常論文]
- 北海道南部に生息するヤドカリ2種における貝殻利用パターンの種間変異津崎尚也, 村上万龍, 石原(安田)千晶, 和田 哲Cancer 30 35 - 48 2021年08月 [査読有り][通常論文]
- Hiroyuki Yamada, Satoshi WadaEvolution 75 7 1850 - 1861 2021年07月 [査読有り][通常論文]
- Prey utilization by Neptunea arthritica (Gastropoda: Buccinidae): predation on gastropods and size-related variationRyusei Yamakami, Satoshi WadaJournal of Molluscan Studies 87 2 eyab016 2021年05月 [査読有り]
- Males display “inverse rapping” as a mating behavior to receptive females in the hermit crab Pagurus nigrofasciaYuina Kido, Satoshi WadaPlankton and Benthos Research 15 3 279 - 288 2020年08月 [査読有り][通常論文]
- 長谷川 稜太, 山田 寛之, 石原 千晶, 和田 哲魚類学雑誌 67 1 11 - 24 一般社団法人 日本魚類学会 2020年04月 [査読有り][通常論文]
Animal personality, defined as consistent individual differences in behavior across time and/or context, has been associated with individual dispersal tendencies in some species. White-spotted char (Salvelinus leucomaenis) populations, often found in above-dam watersheds in Japanese mountain streams, the dams preventing continuous distribution with lower stream reaches, were subject of a behavioral study comparing above-dam and open-stream behavior of fry. Fries were collected from an above-dam area and two open-stream areas within the Kame River system (southern Hokkaido), and personality quantified by measuring a suite of behaviors, such being repeated two-month later. Above-dam fry showed a shorter swimming duration against a novel object and mirror than open-stream fry. The latency time to catch food in above-dam fry tended to be longer than that of the latter. Swimming duration against a novel object and mirror were significantly correlated when data for both groups combined, but not so when data for each group were analyzed independently. These results suggest that personality traits in whitespotted char fry would be shaped by natural selection acting on each habitat, resulting in differing adaptive personality traits.
- Masami M. Tamechika, Kohei Matsuno, Satoshi Wada, Yoichi YusaECOLOGY AND EVOLUTION 10 5 2492 - 2498 2020年03月 [査読有り][通常論文]
Sex allocation theory predicts that the optimal sexual resource allocation of simultaneous hermaphrodites is affected by mating group size (MGS). Although the original concept assumes that the MGS does not differ between male and female functions, the MGS in the male function (MGSm; i.e., the number of sperm recipients the focal individual can deliver its sperm to plus one) and that in the female function (MGSf; the number of sperm donors plus one) do not always coincide and may differently affect the optimal sex allocation. Moreover, reproductive costs can be split into "variable" (e.g., sperm and eggs) and "fixed" (e.g., genitalia) costs, but these have been seldom distinguished in empirical studies. We examined the effects of MGSm and MGSf on the fixed and variable reproductive investments in the sessilian barnacle Balanus rostratus. The results showed that MGSm had a positive effect on sex allocation, whereas MGSf had a nearly significant negative effect. Moreover, the "fixed" cost varied with body size and both aspects of MGS. We argue that the two aspects of MGS should be distinguished for organisms with unilateral mating. - 山田 寛之, 榎本 尊, 和田 哲魚類学雑誌 66 2 221 - 225 一般社団法人 日本魚類学会 2019年11月 [査読有り][通常論文]
Many local populations of white–spotted char (Salvelinus leucomaenis), a widespread Far East Asian species, persist in above–dam areas, even when erosion control dams prevent continuing upstream movement of individuals. Four morphological characters (dorsal fin height, body depth, caudal peduncle depth, and eye diameter) and two behavioral traits (settlement time and number of foraging actions) of S. leucomaenis fry were compared between two tributaries, one above an erosion control dam and the other an unrestricted stream. Dorsal fin height and caudal peduncle depth were smaller, and settlement time during daytime longer in the above–dam fry, which also showed less frequent foraging behavior than unrestricted stream fry during nighttime, suggesting that the former had unsuitable morphology for swimming and a lower wondering tendency. These characteristics may ultimately aid survival of the above–dam population.
- 木戸結菜, 伊與田朋未, 石原(安田)千晶, 和田 哲Cancer 28 7 - 15 日本甲殻類学会 2019年08月 [査読有り][通常論文]
This paper described female guarding avoidance behaviors against precopulatory guarding attempts by males and examines the effect of the number of days until female prenuptial molting on rejection behaviors in the hermit crab Pagurus nigrofascia. We used three types of females in an experiment; (1) ovigerous females (OV–female), (2) females which had not been guarded in the field (NG–female), and (3) females which had been guarded by other males in the field (G–female). We placed a male that had been solitary and a female of either type in a small container, observed the interaction, and compared the female behaviors among the three types of female. The frequencies of retreat and escape from approaching male were highest in OV–females, and lowest in G–females. During male assessment behaviors of females, frequencies of struggle and escape in OV– and G–females were higher than NG–females. 33 of 51 G–females were guarded by males although OV– and NG–females were rarely guarded by males. Many G–females showed rejection behavior during male guarding. However, no significant effect was found in the number of days until the female prenuptial molt on the frequencies of rejection behavior. - テナガホンヤドカリに見られる繁殖期後の大鋏脚の再生石原(安田)千晶, 和田哲Cancer 27 1 - 5 2018年 [査読無し][招待有り]
- Antenna length in the hermit crab Pagurus middendorffii: sexual dimorphism and effect on two types of male-male competitionAyumi Morita, Satoshi WadaBulletin of Fisheries Sciences, Hokkaido University 68 27 - 32 2018年 [査読無し][通常論文]
- 小島早智, 石原(安田)千晶, 和田哲Cancer 25 25 17 - 24 日本甲殻類学会 2016年 [査読有り][通常論文]
- 加我夏美, 石原(安田)千晶, 和田哲Cancer 25 25 9 - 16 日本甲殻類学会 2016年 [査読有り][通常論文]
- Kento Matsuo, Daisuke Tanikawa, Chiaki I. Yasuda, Satoshi WadaMARINE ECOLOGY-AN EVOLUTIONARY PERSPECTIVE 36 4 1391 - 1399 2015年12月 [査読有り][通常論文]
Pagurus hermit crabs have a well-developed right cheliped (major cheliped) and in some species the major cheliped of males is longer than that of females. This paper describes sex-related differences in major cheliped length and regeneration pattern of the major cheliped in the hermit crab Pagurus filholi. We also examined the function of the major cheliped in male-male competition. Major cheliped length of males was longer than that of females in P. filholi. Males regenerated larger chelipeds than females at the first molt after experimentally induced autotomy. Body size growth in males of the regeneration group was less than that in intact males of the control group while there was no significant difference in body size growth of females between regeneration and control groups. Major cheliped length was included in the best model to explain the outcome of male-male competition and thus sexual selection appears to be a causative factor in the sex-related difference of the major cheliped length. Sex-related differences in the regeneration pattern may reflect differences in evolutionary pressures on males for large major chelipeds and females for large body size. - Yukari Hasaba, Chiaki I. Yasuda, Satoshi WadaANIMAL BEHAVIOUR 107 1 - 5 2015年09月 [査読有り][通常論文]
In animals that reproduce sexually, males are often under strong selection to maximize the number of mating opportunities. However, in some iteroparous species, males do not always maximize the allocation of time and energy to the present mating opportunity. Male hermit crabs of the genus Pagurus show precopulatory guarding as a mate acquisition strategy. Although almost all males within this genus guard and compete for receptive females, males of Pagurus filholi differ in how likely they are to do so. To examine the factors explaining the absence of guarding behaviour in P. filholi, a laboratory experiment was conducted that focused on whether either of two receptive females was guarded by solitary males that had been found not paired in the field, had lost a previous male-male contest or had copulated with other females. Solitary males showed a significantly lower frequency of guarding than males with experience of losing or of copulation. In the solitary group, males that moulted within 5 days after the experimental trial did not guard females, and the moulting frequency of nonguarding males was significantly higher than that of guarding males. In further analysis, smaller solitary males were shown to be less likely to guard females. The results of the experiment suggest that males of P. filholi may not always invest as much as possible in the present mating opportunity but may temporarily invest in growth during the 8-month mating season. (C) 2015 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. - Chiaki I. Yasuda, Kento Matsuo, Satoshi WadaBEHAVIORAL ECOLOGY AND SOCIOBIOLOGY 69 8 1287 - 1292 2015年08月 [査読有り][通常論文]
Prior social experience often affects subsequent competitive interactions and their outcomes. Although the effects of prior contest experience have been widely examined, effects of mating experience remain less well examined. We examined, in males of the hermit crab Pagurus nigrofascia, whether males successively copulated with more than one female and whether males with copulation experience differed in their subsequent contest behaviors and probability of winning in male-male contests compared to males without copulation experience. The copulation experience of intruders was manipulated and the contest behaviors compared between mated and unmated groups. Males mated with several females regardless of the male body size. Compared with unmated intruders, intruders with mating experience succeeded more often in taking over females and did so within a shorter period particularly when the male-male contests occurred over females with a long time to molt. These results suggest that mated males of P. nigrofascia overestimate the female quality and/or enhance the competitive performance similar to the "winner effect" that is a positive feedback from prior winning experience to future contests. - Chiaki I. Yasuda, Satoshi WadaCrustacean Research 44 29 - 38 日本甲殻類学会 2015年 [査読有り][通常論文]
Males of the hermit crab Pagurus middendorffii use their major cheliped in male–male contests during the reproductive season. This study examined whether autotomized major chelipeds were regenerated before, during or after the mating season. We reared males that were experimentally induced to autotomize just before the mating season (October). During the mating season (November), few males molted even if they had autotomized their major cheliped. In contrast, males initiated a molt at the end of and after the mating season, and most of the autotomized males regenerated their major cheliped before the end of the rearing period (December). This suggests that regenerated major chelipeds in this study affect events other than mating, particularly perhaps future shell acquisition associated with general activities such as predator avoidance, physiological tolerance and growth. - Chiaki I. Yasuda, Kento Matsuo, Yukari Hasaba, Satoshi WadaANIMAL BEHAVIOUR 96 49 - 57 2014年10月 [査読有り][通常論文]
Prior contest outcomes often affect subsequent contest behaviour (winner/loser effects). If contestants discriminate between familiar and unfamiliar opponents, individual recognition may alter the strength and/or manner of winner/loser effects. We examined whether hermit crabs, Pagurus middendorffii, changed their contest behaviour based on winner/loser effects, whether they distinguished a familiar opponent from an unfamiliar opponent, and how the familiarity with the opponent related to the winner/loser effects in male-male contests. Males of this species show precopulatory guarding behaviour, and male-male contests often occur between a guarding male and an intruder. In contests between unfamiliar males, intruders use self-assessment during the initial contact phase and mutual assessment during the physical combat phase to determine their behaviours. Precopulatory guarding males and females collected in the field were used in two consecutive trials of male-male contests. Losers in the first trial were used as focal intruders in the second trial with (1) a familiar opponent that had won the first trial, (2) an unfamiliar opponent that had won the first trial with another intruder, or (3) a naive opponent with no trial experience. Focal intruders did not alter their aggressiveness against either unfamiliar or naive opponents in the second trial. However, they rarely initiated physical combat against familiar opponents in the second trial. When they initiated combat, they gave up sooner against familiar opponents than against unfamiliar opponents. These results suggest that intruders are able to distinguish familiar opponents from others and decrease their aggressiveness only when they encounter familiar opponents. Our study therefore shows loser effects in P. middendorffii related to the familiarity with the opponent and suggests intruders can obtain information about their opponents during the initial encounter. (C) 2014 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. - Satoshi Wada, Chiaki I. Yasuda, Colin McLayBulletin of Fisheries Sciences, Hokkaido University 64 2 31 - 35 北海道大学大学院水産科学研究科編集出版委員会 2014年 [査読無し][通常論文]
The evolutionary factors of sexual size dimorphism and reproductive characters in Pagurus traversi and P. novizealandiae,are discussed. Investigations and sample collection were conducted in the intertidal area around Kaikoura peninsula, southernisland of New Zealand from 22 February to 23 March 2012. The number of crabs collected was 1198 P. traversi and 318 P.novizealandiae. The degree of size dimorphism ((mean male size)/(mean female size)) was 1.09 and 1.03 in P. traversi and P.novizealandiae, respectively. The fecundity relationship between clutch size and female body size (shield length, mm) in P. traversiwas estimated as log10[clutch size] =1.010 + 0.794 × log10[female size3], indicating that clutch size approximately increaseas an isometric relationship. All males guarded females smaller than themselves in nine precopulatory guarding pairs of P.traversi. However, difference in the mean size between the guarding males (4.79 mm) and other males (4.50 mm) was small(0.29), suggesting that large size advantage might be weak in mate acquisition compared with other species of the genus Pagurus. Weak evolutionary selection pressure acting on male body size may explain relatively small degree of sexual size dimorphism inP. traversi. - Kento Matsuo, Chiaki I. Yasuda, Satoshi WadaCrustacean Research 43 43 41 - 46 日本甲殻類学会 2014年 [査読有り][通常論文]
Major cheliped is used in shell selection in the hermit crab Pagurus middendorffii. This study examined how loss of the major cheliped due to autotomy affected shell selection behavior and whether shell-size preference was affected. Crabs after autotomy changed shells less frequently than intact crabs. However, there was not a significant difference in shellsize preference between autotomized crabs and intact crabs. Since autotomy occurs during fleeing from a predatory attack in the field, subsequent reduction of frequency of changing shells might suppress the risk of predation for crabs. - Chiaki I. Yasuda, Kento Matsuo, Satoshi WadaPlankton and Benthos Research 9 2 122 - 131 2014年 [査読有り][通常論文]
Most crustaceans are known to regenerate their appendages after losing them, and the pattern of regeneration may be related to its function. The pattern of regeneration of the right major cheliped was examined after experimentally induced autotomy and its behavioral function during male-male contests for mates was investigated in the hermit crab Pagurus middendorffii. Males with an autotomized major cheliped regenerated it at the first molt after autotomy and showed smaller growth in body size than in control males. The shape of the regenerated cheliped was more slender than the original, implying that the regenerated major cheliped would be less robust and weaker than previously. The length of the major cheliped of an owner male (guarding a female at the start of a dyadic contest) and the body size of an intruder affected whether or not the contest escalated, but the major cheliped length of the intruder and the body size of the owner determined the outcome of the escalated contest. The intruder used the major cheliped as an offensive weapon to take the female away from the owner by force after the contest escalated. The owner often moved the major cheliped forward, similar to a fencing weapon, before escalation. Such movement of the owner seems to be effective to prevent the intruders from approaching, and the regenerated cheliped of the owner may not require much robustness and strength as a defensive weapon before escalation. Rapid regeneration of the major cheliped in P. middendorffii would therefore be beneficial to minimize the disadvantages incurred by loss of the major cheliped. - Hisae Ojima, Satoshi WadaPlankton and Benthos Research 8 1 38 - 45 2013年06月18日 [査読有り][通常論文]
Some animals show multiple behavioral responses after detection of chemical cues indicating a predation threat. Individuals of the high intertidal periwinkle, Littorina sitkana, showed two contrasting anti-predation responses, immobile cautiousness and active fleeing, against the predatory crab, Hemigrapsus sanguineus. This study examined the combined effects of chemical cues of predation threat (crab, crushed conspecific, mixed crab and crushed conspecific, and control), body size, and time (morning, mid-day and late-evening) on the anti-predation behaviors of L. sitkana. The cautious response of L. sitkana was strongest under the crab treatment, with the earliest fleeing response appearing when presented with the mixed chemical cue of crabs and crushed conspecifics. Time of day also affected the anti-predation responses, with a longer cautious response during late-evening than mid-day under control conditions, and no significant difference between late-evening and mid-day in response to the three types of chemical cues of predation threat. The fleeing response occurred more rapidly during late-evening than midday for the four types of chemical conditions there was no significant difference between morning and mid-day under the control condition and it occurred more rapidly during morning than mid-day under the three predation threat conditions. Larger individuals showed longer cautious responses for all conditions and remained submerged in seawater for longer under the three predation threat conditions. It is suggested that the level of predation risk may be assessed by L. sitkana and used to elicit the appropriate of the two contrasting anti-predation responses. © The Japanese Association of Benthology. - 古屋野太一, 伊藤 篤, 和田哲日本ベントス学会誌 68 1 1 - 6 日本ベントス学会誌編集委員会 2013年 [査読有り][通常論文]
- Yutaro Suzuki, Chiaki Yasuda, Fumio Takeshita, Satoshi WadaMARINE BIOLOGY 159 9 1991 - 1996 2012年09月 [査読有り][通常論文]
Male mate choice has recently been reported in some animals with male-male competition. In the laboratory, we examined whether males choose their mates based on female quality that was indicated by body size and/or days to prenuptial molt, and the effects of female quality on male-male competition in the hermit crab Pagurus nigrofascia. We collected samples from April to May 2009 at an intertidal shore in Hokkaido, Japan (41A degrees N, 140A degrees E). When a male simultaneously encountered two receptive females in the mate choice experiment, males chose females which require less time to molt. When a male guarding a female with less time to molt was challenged by an intruder, the guarding male defended the female for a longer period and was more likely to win the contest. These results indicate that male P. nigrofascia use time to molt to discriminate between females. - Chiaki Yasuda, Fumio Takeshita, Satoshi WadaANIMAL BEHAVIOUR 84 2 385 - 390 2012年08月 [査読有り][通常論文]
Assessment of their own resource-holding potential (RHP) and that of their opponent affects the behaviours individuals use in contest competition. Contestants may use their own RHP and/or the relative RHP of opponents to make decisions and may switch these two assessment tactics during fighting. In male-male contests of hermit crabs Pagurus middendorffii, we examined whether contestants switch assessment tactics and whether they assess body size or major cheliped size as an index of RHP. Males of this species show precopulatory guarding behaviour, and male-male contests often occur when males guarding females encounter intruder males. We conducted trials of dyadic contests to investigate the assessment tactics in two phases of the contest: initial and combat. Intruders gave up the contest without escalating to physical combat when they were smaller. When physical combat occurred, it lasted longer if the difference in size of the major cheliped between guarding males and intruders was small, and males with a larger major cheliped than the opponent had a higher probability of winning the contests. These results suggest that P. middendorffii uses its own body size during the initial phase of a contest and relative major cheliped size during the combat phase to assess RHP. (C) 2012 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. - Fumio Takeshita, Satoshi WadaJOURNAL OF CRUSTACEAN BIOLOGY 32 4 673 - 676 2012年07月 [査読有り][通常論文]
The second gnathopods of caprellid male amphipods are larger than the ones observed in females. The second gnathopods are armed with a propodus or tooth that is associated with a poison producing gland, by which male-male contests lead to fatal outcomes. Here we observed the ultrastructure of the second gnathopods by scanning electron microscopy and compared the relationship between the number of pores in the poison tooth and body length among the males of four caprellid species: Caprella acanthogaster, C. bispinosa, C. svaura, and C. penantis. All species possess pores on the poison tooth, and the number of pores increased with body size. The number of pores also differed among specimens of the four species. Furthermore, in males of three caprellid species, except for C. penantais, we found additional pores at the tip of the dactylus of second gnathopods. The number of pores on the tip of the dactylus did not increase with body length, and the average number of them differed among the three species. Although it is not known if venom is released front the pores of both structures, larger individuals that possess more pores on the second gnathopods could have a competitive advantage in male-male competition. - Tanikawa, D, C. Yasuda, Y. Suzuki, S. WadaJapanese Journal of Benthology 67 1 15 - 19 日本ベントス学会 2012年 [査読有り][通常論文]
Males of the hermit crab Pagurus filholi guard females until spawning, and male-male contest often occur when guarding males encounter other males. A contest comprises two phases, initial contact and physical combat, and larger males typically win. We conducted male-male contest experiments to examine whether body sizes of both sexes of P. filholi and female receptivity affect whether and when a contest escalates to physical combat, as well as contest duration and outcome. For each experimental trial, a pair, comprising a “pairing male” and a “pairing female”, and a second male (“intruder”) were placed into a small container, and their behaviors were observed for 15 minutes. Each intruder had been guarding a female in the field but we removed this female (“removed female”) just before the trial. All pairs in the field were reconstructed each after trial to quantify female receptivity. This was done by checking each female for spawning every day. As an index of size, we measured shield length (length of calcified anterior portion of cephalothorax) of all crabs. In the trials, large size of the intruder and high receptivity of the removed female significantly shortened the time until the onset of physical combat. Intruders needed more time to take over the pairing females and were less likely to win the contests when the intruders were small, the pairing males were large, and the removed females were large. Body size and receptivity of the pairing female had no effect on the process and the outcome of male-male contest. These results suggest that a male P. filholi can assess the quality of female it is guarding and remember its assessment for at least a short period. Asymmetry between contestants in this memory store for female quality could affect the process and the outcome of male-male contests in P. filholi.
Contents of supplementary materials: Appendix 1: Explanation of movie files, Mov 1: Male-male contest, Mov 2: Cessation of male contest, Mov 3: No guarding after takeover. - Abe, S, S. Tashiro, F. Takeshita, S. WadaBulletin of Fisheries Sciences, Hokkaido University 62 2 29 - 41 北海道大学大学院水産科学研究科 2012年 [査読有り][通常論文]
ニホンザリガニCambaroides japonicusは北海道から北東北に分布する日本固有の純淡水産甲殻類である。淡水ザリガニ類の多くの種では局所個体群の遺伝的独立性が高いため,生物・物理環境の異なる生息地間でみられる生活史形質の変異は遺伝的変異に起因する可能性が高い。本研究の目的は,北海道南部におけるニホンザリガニの繁殖形質を記載して,本種を保全するための基礎的な知見を得ることである。本研究では,北海道南部に位置する6地点で野外調査をおこない,体サイズ,抱卵・抱仔メスの出現時期,抱卵数,卵・幼生サイズを記載した。そしてこれらの結果を本種の他個体群及び他種と比較した。 - Chiaki Yasuda, Yutaro Suzuki, Satoshi WadaMARINE BIOLOGY 158 10 2327 - 2334 2011年10月 [査読有り][通常論文]
Functions of the major cheliped in pagurid hermit crabs have been studied in fights for shells. The major cheliped often shows sexual size dimorphism, suggesting that sexual selection favors the development of the male major cheliped. The function of the major cheliped in male-male competition was examined in Pagurus nigrofascia collected from April to June 2009 on the intertidal rocky shore in southern Hokkaido, Japan (41 degrees N, 140 degrees E). Sexual size dimorphism of the major cheliped was observed, and precopulatory guarding males had larger major chelipeds than solitary ones. Guarding males used the major cheliped to deter intruders during competitive interactions. Males without a major cheliped were disadvantaged even if they were larger than opponents and had ownership. Cheliped size affected the outcomes of contests between similar sized males. This suggests that the male major cheliped in P. nigrofascia protects mates from competitors and, consequently, enhances male mating success. Sexual selection may favor the development of the major cheliped in male pagurids. - Hiromi Hasegawa, Satoshi Wada, Masakazu Aoki, Keiji WadaJOURNAL OF THE MARINE BIOLOGICAL ASSOCIATION OF THE UNITED KINGDOM 91 4 893 - 896 2011年06月 [査読有り][通常論文]
The preference for two shell species, Monodonta labio form confusa and Thais clavigera, was compared between two populations of the hermit crab Pagurus filholi from Oura Bay, Shimoda, central Japan and from Hakodate Bay, Hakodate, northern Japan. Hermit crabs from Oura Bay preferred T. clavigera to M. labio form confusa, whereas crabs from Hakodate Bay preferred M. labio form confusa. The shell of T. clavigera was more effective against desiccation and high temperature stress but heavier than M. labio form confusa. The preference of P. filholi from Oura Bay for T. clavigera may be attributable to the greater requirement for protection against higher physical stresses, even though a higher energetic cost related to the shell weight is incurred. - Fumio Takeshita, Roberto Carlos Lombardo, Satoshi Wada, Yasuhisa HenmiANIMAL BEHAVIOUR 81 3 661 - 666 2011年03月 [査読有り][通常論文]
The reproductive strategy of one sex often imposes fitness costs on the other. In crustaceans, precopulatory mate guarding often imposes reproductive costs on females. In iteroparous species with indeterminate growth, such costs may affect not only current reproduction but also growth and lifetime fecundity. We investigated the cost imposed by male mate guarding on the long-term reproductive fitness of females in the skeleton shrimp Caprella penantis. We kept skeleton shrimps for 50 days in three different sex ratio treatments: male biased, even and female biased. Five female fitness components were recorded: survival rate, growth rate, number of clutches, clutch interval and average number of juveniles. Occurrence and duration of guarding increased in the male-biased treatment, indicating that males responded to changes in mate availability through increased guarding. Females under the male-biased sex ratio showed reduced growth rate owing to the longer guarding duration and were consequently smaller. No significant difference between treatments was found in the number of and interval between clutches, but, compared with the even sex ratio treatment, females in the male-biased treatment produced fewer juveniles on average than those in the female-biased treatment. These results indicate that extended guarding duration imposes long-term costs on female fitness in the form of decreased growth and low offspring production. (C) 2010 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. - Male mate choice in hermit crabs: prudence by inferior males and simple preference by superior malesSatoshi Wada, Yuusei Arashiro, Fumio Takeshita, Yasutoki ShibataBEHAVIORAL ECOLOGY 22 1 114 - 119 2011年01月 [査読有り][通常論文]
In species with both male-male competition and male mate choice, inferior males may make different mate choice decisions from superior males. Males of the intertidal hermit crab, Pagurus middendorffii, are known to conduct precopulatory guarding and to adjust the threshold for guarding according to social parameters, such as encounter rate with females, competitor size, and sex ratio. Larger males are stronger in male-male competition during guarding in this species. We here tested whether male of P. middendorffii initially guarding a smaller female exchanged partners when the male encountered a larger receptive female and whether large and small males chose potential mates on the basis of body size and/or time needed for guarding when a male simultaneously encounters 2 females. When a male guarding a smaller receptive female encountered a larger receptive female, the male assessed the larger female and exchanged his partner only in cases of a large difference in body size between the 2 females, suggesting that males of this species could choose their mates based on female quality even during guarding. When a male simultaneously encountered 2 receptive females, small males showed the prudent mate choice by balancing female traits between larger body size and shorter time until breeding, whereas large males showed preference for larger females. The distinct preference exhibited by males of different size classes is concluded to be an adaptive response to the size-dependent risk of losing the female during guarding. - Yoshii, T, F. Takeshita, S. WadaJapanese Journal of Benthology 64 25 - 31 JAPANESE ASSOCIATION OF BENTHOLOGY 2009年 [査読有り][通常論文]
Reproduction carries costs, in terms of growth, survival, and future reproduction, because reproduction entails the expenditure of energy and time that could be used for other functions. Male Pagurus hermit crabs engage in precopulatory mate guarding behavior for a period of up to several days, and this guarding behavior may entail costs for males. We investigated whether precopulatory mate guarding depresses feeding rate and molting frequency as a cost of reproduction for males in the hermit crab Pagurus nigrofascia. Males were discriminated into the following three size classes: small males that were not observed to guard females, middle-sized males, and large males that guarded females. In the field, molting frequency of the large males was significantly lower than that of the other two size classes. The feeding activity of males was greatly depressed while they were engaged in guarding behavior. The duration of guarding was affected by sex ratio in laboratory experiments, the total guarding time increasing along with the number of mates. Molting frequency did not differ significantly among male crabs under the different sex ratios, however. We suggest that precopulatory mate guarding may entail a reproductive cost for males of P. nigrofascia due to depression of feeding activity although this cost may be compensated for by higher feeding activity before and/or after guarding. - Hasegawa, H, S. Wada, M. Aoki, K. WadaPlankton and Benthos Research 42 72 - 76 2009年 [査読有り][通常論文]
- Satoshi Wada, Takashi Oba, Kazuyoshi Nakata, Atsushi ItoMARINE BIOLOGY 154 3 501 - 507 2008年05月 [査読有り][通常論文]
Interval between reproductive events is an important factor for iteroparous animals because it determines the number of clutches throughout life. This study examined whether female size, clutch size, shell size and prenuptial molting affected the clutch interval in the hermit crab Pagurus nigrivittatus. Precopulatory guarding pairs of P. nigrivittatus were sampled in the field and kept in the laboratory until the female extruded eggs. The clutch interval of each female was assessed as one of two types of relatively "short" and "long" intervals by checking whether the guarded female had eggs and/or egg cases from the preceding brood or not when the guarding pair was collected. The clutch interval was longer in females with prenuptial molting than those without molting and these females usually grew larger at the prenuptial molt. This suggests that female P. nigrivittatus with a long interval might allocate energy into growth at the expense of the number of clutches during the current reproductive season. The allocation to growth is theoretically predicted to decrease with female size. Gastropod shell size is also known to affect the reproductive activity in hermit crabs. However, female size did not significantly affect the clutch interval in P. nigrivittatus, and the effect of gastropod shell size on clutch interval was not consistent with previous empirical studies. These results may be caused by differences in the gastropod species of shell occupied by the females of P. nigrivittatus. - Takashi Oba, Satoshi Wada, Seiji GoshimaJOURNAL OF THE MARINE BIOLOGICAL ASSOCIATION OF THE UNITED KINGDOM 88 1 103 - 109 2008年02月 [査読有り][通常論文]
The distribution, reproductive biology and shell utilization pattern of two sympatric hermit crab species in Akkeshi, north-eastern Hokkaido, were examined. Although spatial distributions of Pagurus midendorffii and P. brachiomastus highly overlapped and their body sizes were similar, their shell utilization and breeding season markedly differed. Since interspecific differences in the shell utilization pattern agreed with the experimentally determined shell preference difference, we conclude that the interspecific difference in shell preference results in the shell utilization patterns observed in the field. The interspecific difference in the reproductive period, shell utilization pattern and shell preference are concluded to be factors that allow the coexistence of the two Pagurus species in Akkeshi. This study is an example of resource partitioning by coexisting hermit crabs. - Temporal allocation pattern between reproduction and growth within a breeding season of the hermit crab Pagurus nigrivittatusWada, S, T. Oba, K. Nakata, A. ItoCrustacean Research 37 67 - 73 2008年 [査読有り][通常論文]
- 函館近辺の海岸でみられるヤドカリたちの見分け方と繁殖生態和田哲Oshimanography 15 17 - 18 2008年 [査読無し][通常論文]
- Satoshi Wada, Atsushi Ito, Azusa MimaMARINE BIOLOGY 152 6 1263 - 1270 2007年11月 [査読有り][通常論文]
Molting and breeding entail major energetic costs for female crustaceans. However, females of some hermit crabs perform a molt immediately prior to copulation (prenuptial molt). The evolutionary significance of the prenuptial molt was examined in Pagurus hermit crabs, and two hypotheses were tested: (1) prenuptial molt might enhance the success of the present clutch by cleaning the pleopods of females and thereby preventing eggs from being dislodged from the pleopods, and (2) prenuptial molt might function for growth and increase future fecundity at the cost of energetic expenditure on the present brood. Although these hypotheses are not mutually exclusive, our results rejected the former hypothesis and supported the latter hypothesis. All four Pagurus species examined showed significant negative relationships between prenuptial molting and continuity of breeding; i.e., they showed high molting frequency after they had a long rest period from breeding. Females of P. minutus increased their size through the prenuptial molt, and showed a decreased clutch size due to the molt. The number of dislodged eggs increased if females molted in P. minutus. These results suggest that hermit crabs undergoing a prenuptial molt might not gain any clear immediate advantage of enhanced survival of eggs in the present clutch, and that the prenuptial molt would mainly contribute to growth. - Ryo Sakamoto, Atsushi Ito, Satoshi WadaJOURNAL OF THE MARINE BIOLOGICAL ASSOCIATION OF THE UNITED KINGDOM 86 6 1401 - 1405 2006年12月 [査読有り][通常論文]
The response of the shore crab Gaetice depressus to predation risk stimuli of either the octopus Octopus vulgaris or crushed conspecifics was examined at two different time phases in the activity rhythm (active and inactive period) by laboratory experiments. When octopus chemical stimuli were introduced to the experimental aquarium, the crab activity decreased in the active period (night) but not in the inactive period (daytime). When the chemical stimuli of crushed G. depressus were introduced, the activity of the crabs increased in the inactive period although the stimuli decreased the activity in the active period. This indicates that G. depressus adjust their anti-predator response according to a combination of the type of predation risk and also the activity rhythm. - A Ito, S WadaJOURNAL OF ETHOLOGY 24 1 45 - 49 2006年 [査読有り][通常論文]
Intrasexual copulation and mate discrimination by Nodilittorina radiata (Gastropoda: Littorinidae) were studied on a concrete breakwater at Hakodate Bay, southern Hokkaido, Japan. Intrasexual (male-male) copulations were observed in 4.7-21.1% Of Copulating pairs on the shore. As females were relatively larger than males and males copulated with females larger than themselves, we hypothesized that males choose potential mates larger than themselves. However, two male mates showed no significant size preference in intrasexual copulations, suggesting that males do not choose relatively larger individuals as mates. In a laboratory mate-choice experiment, male N. radiata preferred to mate with females, indicating precopulatory sex identification. They copulated with males, however, at the frequency of 37%, perhaps because of sex misidentification. - Goshima, S, S. Minouchi, K. Yoshino, S. WadaBiology of Anomura II. Crustacean Research, Special Issue 6 87 - 94 2006年 [査読有り][通常論文]
- S Wada, A Mima, A ItoJOURNAL OF THE MARINE BIOLOGICAL ASSOCIATION OF THE UNITED KINGDOM 85 4 889 - 894 2005年08月 [査読有り][通常論文]
Reproductive phenology among temperate hermit crabs, reproductive seasons of nine sympatric species and some reproductive characteristics of four Pagurus species were investigated in Tosa Bay, southern Shikoku, Japan. Females of P. filholi, P. maculosus, P. minutus and P. nigrivittatus had clutches mainly in winter and were found to breed multiple clutches within each reproductive season while four Diogenidae species and P. japonicus mainly reproduced in summer, suggesting that interspecific variation in reproductive phenology of temperate hermit crabs might be determined by allopatric adaptation with phylogenic constraints. There was interspecific variation in the length of reproductive seasons among the four Pagurus species and the variation was considered to reflect the interspecific difference in the number of clutches per reproductive season, not in the ovigerous period per clutch. The length of reproductive seasons among the four species seemed to relate to maturity size and/or interspecific differences in thermal adaptation. - Ito, A, T. Koyano, Y. Okamoto, M. Ohno, S. Wada水産増殖 53 1 23 - 30 日本水産増殖学会 2005年 [査読有り][通常論文]
土佐湾内の浦ノ内湾の竜の防波堤に, 人工海藻で作成した幼生コレクターを設置して, イセエビプエルルス幼生の着底様式を調べた。採集されたイセエビ幼生の発達ステージはコレクターの設置期間によって異なり, 発達後期のプエルルス幼生は翌日にはほとんど採集されず, 3日目以降になると増加した。このことから, 着底後のプエルルス幼生は稚エビになるまで, あまり移動しないことが示唆された。人工海藻の色に対する野外と室内での選択実験では, 一貫した傾向は認められず, 藻体の色がプエルルス幼生を誘引する要因になっている可能性は低いことが示唆された。また, プエルルス幼生が稚エビへと変態するまでの日数は着底場所の有無によって変わらなかった。このことは一度着底したプエルルス幼生は変態のタイミングを変更できないことを示している。 - T Sato, M Ashidate, S Wada, S GoshimaMARINE ECOLOGY PROGRESS SERIES 296 251 - 262 2005年 [査読有り][通常論文]
Potential sperm limitation in a fished population of the spiny king crab Paralithodes brevipes was investigated in controlled laboratory experimental and field studies. The laboratory experiments examined the effects of male size and mating frequency on their reproductive potential and the recovery rate of exhausted sperm. The spawning success and fertilization rate of females decreased as the male mating frequency increased. The effects of increased male mating frequency on the spawning success of females and fertilization rates differed between male size classes. Male size and mating frequency have great influences on sperm limitation. Males showed little capacity to regenerate sperm, increasing the likelihood of limited sperm supply to females in fished population with low numbers of males due to male-selective fishing regulations. The field studies examined the structure of a fished population of F brevipes in Hamanaka, eastern Hokkaido, before and after a change in the fishery regulations that permitted smaller males to be harvested. The results showed that a change in the sex ratio occurred after the fishery regulations were introduced, skewing the population towards females. The results also showed a decrease in the mean male size in the fished population. The results also indicated that a significant percentage of males (42.2%) had depleted sperm reserves just after the reproductive season. Overall, the results indicate that sperm limitation could occur in this fished population of R brevipes. These observations may warrant a review of the current fishing regulations, particularly the minimum legal size. - Ito, A, S. WadaBenthos Research 60 11 - 16 2005年 [査読有り][通常論文]
- Koyano, T, S. Wada水産増殖 52 2 129 - 132 日本水産増殖学会 2004年 [査読有り][通常論文]
2002年4月から2002年12月まで土佐湾内の浦ノ内湾において, マガキガイの月ごとの密度変化と5年間の漁獲量の変化を調査した。その結果, 月ごとの密度変化は明瞭な季節的変動が見られず, 繁殖期に高密度となる他地域の研究報告と異なっていた。この理由として, 本種の漁獲が本調査地の高密度形成を妨げ, 本調査地では本種の再生産がほとんどおこなわれていないことが示唆された。しかし, 1998年から2002年までの漁獲日数あたりの漁獲量には変化が見られなかったため, 他地域から加入した幼生が浦ノ内湾における漁獲個体群の安定化に貢献していると考えられる。 - Higuchi, M, T. Koyano, A. Ito, S. Wada水産増殖 52 3 251 - 258 日本水産増殖学会 2004年 [査読有り][通常論文]
高知県浦ノ内湾及び沖ノ島周辺で採集されたマガキガイの捕食者防御行動について室内実験をおこなった。本種は成長に伴い貝殻外唇部が肥厚するので, 外唇部が厚さと防御行動の関係に着目した。ほぼ同一サイズの個体を用いた室内実験の結果, 捕食者であるソメンヤドカリは外唇部の薄い個体を選択的に捕食したが, 外唇部の肥厚によって捕食者防御行動に対する明瞭な影響は認められなかった。また, 本種の行動に対する同一水槽内のソメンヤドカリの影響は認められなかった。ソメンヤドカリに捕らえられたマガキガイは多量の粘液を分泌したが, 粘液の有無による本種の行動においても有意な違いは認められなかった。一方, つぶしたマガキガイが入った水槽では, コントロール条件に比べて本種が有意に早く完全埋没 (自分の貝殻が底質表面から見えなくなるまで潜砂した状態) に至った。 - A Mima, S Wada, S GoshimaOIKOS 102 1 104 - 110 2003年07月 [査読有り][通常論文]
Hermit crabs have two antipredator tactics: taking refuge in its shelf and fleeing. We examined the following two hypotheses using the hermit crab Pagurus filholi: (1) hermit crabs change their preference for shell types that they take refuge in and/or change the timing of fleeing (i.e. the duration of refuge in the shelf) when they perceive a predator threat. (2) the type of shell that a hermit crab occupies affects the fleeing tactic of the individual. Under the stimulus of a crushed conspecific, hermit crabs changed neither their preference for shell species nor their refuge duration, On the other hand, under the stimulus of the predatory crab Gaetice depressus, hermit crabs, increased their preference for Batillaria cumingi shells, which provide superior protection against predators, and shortened their refuge duration in the shells even when they occupied those effective against predation. Refuge duration was longer in B. cumingi shells than in the more vulnerable shells of Homalopoma sangarense These results suggest that both antipredator defences (changing shell and timing of fleeing) are induced by the stimulus of a predator, and the timing of fleeing is affected by the shell type occupied. - Takahashi, M, M. Higuchi, S. WadaBulletin of Marine Sciences and Fisheries, Kochi University 22 53 - 60 高知大学海洋生物教育研究センター 2003年 [査読無し][通常論文]
Distribution pattern, reproductive mode and aggressive behavior of the sea anemones Anthopleura uchidai and A. asiatica from rocky coast of Kochi were studied. Anthopleura uchidai occurred on the crevices and hollows of rocks in splash area and A asiatica did on the underside of stones in intertidal area. The frequency of occurrence in aggressive response between two neighbor individuals differed between species was higher in A. uchidai than in A. asiatica, suggesting that sexual reproduction might be dominant in A. uchidai while A. asiatica might frequently perform asexual reproduction. Anthopleura uchidai more often used acrorhagi for aggression than A. asiatica. Distances between individuals and between colonies were similar between the two species, although A. uchidai formed larger colony than A. asiatica. This suggests that dominant reproductive mode and the intensity of aggressive interaction might not affect local distribution pattern in the two sea anemones. - Akamatsu, K, S. WadaBulletin of Marine Sciences and Fisheries, Kochi University 22 61 - 64 高知大学海洋生物教育研究センター 2003年 [査読無し][通常論文]
The effect of light condition on size preference for prey clam (Ruditapes philippinarum) and foraging site of Japanese spiny lobster Punulirus japonicus was studied in the laboratory. Light condition was controlled by whether a black curtain was covered over experimental tank or not. Lobsters (60-91mm in carapace length) preferred small clams (>15mm in shell length), and no effect of light condition was detected on the prey size preference. However, lobsters seemed to forage around feeding spot under dark condition while they did around shelter under light condition, suggesting that predation pressure for lobsters might vary with light level in the field. - Reproductive characters of the hermit crab Pagurus proximus Komai 2000 in Hakodate Bay, southern Hokkaido, JapanWada, S, A. MimaCrustacean Research 32 73 - 78 2003年 [査読有り][通常論文]
- T Kobayashi, S Wada, H MukaiJOURNAL OF CRUSTACEAN BIOLOGY 22 1 135 - 142 2002年02月 [査読有り][通常論文]
Several peracarid crustaceans have been shown to engage in extended maternal care for their growing offspring after the juveniles hatch from the brood pouch of the female. In this study, we describe the maternal care of the epibenthic gammaridan Parallorchestes ochotensis Brandt and examine its ecological implications. The juveniles stayed in the female's expanded brood pouch for at least seven weeks after hatching. The duration of extended maternal care of P. ochotensis was comparatively longer and the growth of P. ochotensis juveniles slower than reported for other epibenthic peracarids. The juveniles molted at least twice whilst in maternal care. This species probably has an annual life span, and they reproduce only once a year. In P. ochotensis, maternal care was shown to constrain juvenile growth in the experimental predator-free conditions, contrary to other epibenthic peracarids. Most epibenthic peracarid species with extended maternal care are suspension feeders, but P. ochotensis is an herbivore so probably maternal care of this species limits juvenile feeding opportunities and results in a decrease of juvenile growth. However, where normal predation exists, maternal protection contributes significantly to juvenile survival. In P. ochotensis, to enhance relatively low fecundity in conditions where predation pressure is high, extended maternal care for relatively long periods is necessary to protect offspring even if it constrains juvenile growth. - Mima, A, H. Ohmori, S. Wada, S. GoshimaBenthos Research 57 85 - 89 2002年 [査読有り][通常論文]
- Satoshi WadaBenthos Research 56 1 43 - 46 Japanese Association of Benthology 2001年 [査読有り][通常論文]
- S Goshima, M Kanazawa, K Yoshino, S WadaJOURNAL OF CRUSTACEAN BIOLOGY 20 4 641 - 646 2000年11月 [査読有り][通常論文]
Male size at maturity is important information for management of crab fisheries. Morphometric and/or gonadal maturity, which have been used to estimate size at maturity for many male crustaceans, were examined as potential indicators of functional maturity using small, unfished stone crab Hapalogaster dentata as a model species. Morphometric size of maturity as estimated by the change of the allometric relationship between carapace length (CL) and chela height was 5.2 mm CL. The size at gonadal maturity as estimated by histological examination of the gonad and vasa deferentia was 5.3 mm CL. The functional size at maturity as estimated by observing precopulatory guarding pairs in the field was 9.5 mm CL, much larger than the former two estimates. Size-assortative mating was observed between guarding males and guarded females. Female choice for larger males and advantage of the larger males in mating fights may be the reasons why such discrepancy between morphometric and/or gonadal maturity and functional maturity exist. We suggest that minimum legal size limit for decapod crustaceans should be determined by the functional maturity-actual size to participate in mating-and that the size of functional maturity is useful information for conservation-oriented management. - S Wada, H Kitaoka, S GoshimaJOURNAL OF CRUSTACEAN BIOLOGY 20 3 474 - 478 2000年08月 [査読有り][通常論文]
Reproductive traits of Pagurus lanuginosus are described and compared with three sympatric, congener species. Female P. lanuginosus mature at about 5 mm shield length, spawn clutches in autumn and spring, and are considered to have two or more clutches per year. Among the four sympatric Pagurus species (P. lanuginosus, P. middendorffii, P. filholi, P. nigrofascia), spawning season, hatch-out season, annual spawning times, maturity size, and incubation period differed. Specific differences in annual spawning times and some related traits may be explained by differences between species in maximizing the fitness component. Species with several clutches each year and a short incubation may segregate settlement timing to reduce intra- and interspecific competition for unpredictably supplied small shells among settling and newly settled crabs and, thus, maximize the number of clutches per annum. Alternatively, species with single annual clutch, early spring hatch out, and long incubation may be selected to maximize larval survival and/or settlement success if early spring is the optimal season for larval settlement success. - S Wada, M Ashidate, K Yoshino, T Sato, S GoshimaJOURNAL OF CRUSTACEAN BIOLOGY 20 3 479 - 482 2000年08月 [査読有り][通常論文]
The effects of sex ratio on the spawning frequency of females and on male mating behavior were examined in the spiny king crab, Paralithodes brevipes. Two types of guarding behavior were categorized based on when the male began guarding the female, that is, pre- and post-molting types, when the male starts guarding the female either before or after her molt, respectively. Males reared under a female-biased sex ratio more often showed the post-molting type than did males reared under an even ratio. Guarding duration for the pre-molting type, from the start of guarding to female molting, was significantly longer when the sex ratio was even than when females were more numerous (female:male ratio = 5:1). While there was no significant difference in the molting frequency of females between the two sex ratios, frequencies of egg extrusion were significantly lower for the female-biased ratio than for the even sex ratio. These results suggest that the sex ratio affects the mating behavior of P. brevipes and might be an important factor to manage wild populations and to produce seed crabs effectively in nursery ranks. - WADA S.北海道大學水産學部研究彙報 51 1 1 - 11 2000年03月 [査読無し][通常論文]
- Satoshi WadaBulletin of Marine Sciences and Fisheries, Kochi University 20 1 - 14 2000年 [査読無し][通常論文]
- アラレタマキビ Nodilittorina radiata におけるつま先立ち行動Satoshi Wada, Atushi ItoBulletin of Marine Sciences and Fisheries, Kochi University 20 15 - 24 2000年 [査読無し][通常論文]
- S WadaJOURNAL OF THE MARINE BIOLOGICAL ASSOCIATION OF THE UNITED KINGDOM 79 5 953 - 954 1999年10月 [査読有り][通常論文]
The effects of shell resource and interspecific competition on sexual size dimorphism of the hermit crab, Pagurus middendorffii (Decapoda: Paguridae), were examined from population comparisons. Degree of size dimorphism and mean shell size occupied by male and female P. middendorffii differed among adjacent sites, and there was a significant correlation between them. Although most large It middendorffii occupied large Chlorostoma lischkei shells in both shell-limited and shell-unlimited populations, P. lanuginosus, a sympatric species, occupied large C. lischkei shells more frequently than P. middendorffii did in a shell-limited population. Environmental factors, shell availability and interspecific competition for shells, might play important roles in determining the degree of sexual size dimorphism of P. middendorffii. - S Wada, K Tanaka, S GoshimaJOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY 239 2 289 - 298 1999年06月 [査読有り][通常論文]
The effects of sex ratio, competitor size, and the encounter rate with females on the duration of male precopulatory guarding were tested in the hermit crab Pagurus middendorffii (Brandt, 1851) to examine how guarding duration varies in relation to social factors. Size and owner advantages in male-male contest competition were also examined. Larger and owner males were stronger competitors than smaller and challenger males, respectively. Males guarded females earlier and, consequently, longer when the sex ratio was more male biased, when size differences between competitor sizes were small, and when encounter rates were low, which are consistent with theoretical predictions. However, contrary to these predictions, small males did not guard earlier than large males when size differences were large. These results suggest that males might assess not only the operational sex ratio based on the encounter rate with females but also their competitive ability relative to other males and the possibility of successful guarding. (C) 1999 Elsevier Science B.V. All rights reserved. - Wada, S, K. Ishizaki, H. Kitaoka, S. GoshimaBenthos Research 54 1 9 - 16 Japanese Association of Benthology 1999年 [査読有り][通常論文]
- Goshima, S, M. Ikegawa, T. Sonoda, S. WadaBenthos Research 54 2 87 - 97 Japanese Association of Benthology 1999年 [査読有り][通常論文]
- S Goshima, T Kawashima, S WadaECOLOGICAL RESEARCH 13 2 151 - 161 1998年08月 [査読有り][通常論文]
Males of the hermit crab, Pagurus filholi, often grasp the edges of shells occupied by females and drag them during the mating season. This behavior was experimentally confirmed to be a precopulatory guarding behavior displayed by males for ripe females, and males were found to recognize females which were within about 5 days of spawning. Most theoretical models for mating preference assume the choosing ses (the male in the present case) has complete reproductive information about potential mates, and predict that males will preferably choose more fecund females and/or females that will require less guarding time (i.e. that will spawn sooner) as partners. Several male-choice experiments between two ripe females, both previously guarded by other males, were carried out to examine the above predictions. Males did not prefer females of larger size, higher fecundity or with less time remaining until spawning. These results suggest that males may not have complete information about potential partners, rather that male hermit crabs may adopt a mating strategy of pairing with the first ripe female they encounter. Even with such incomplete mate assessment, males may enhance their reproductive success by recognizing ripe females that will spawn within a given time (about 5 days in the present case). - S Wada, H Ohmori, S Goshima, S NakaoANIMAL BEHAVIOUR 54 1 - 8 1997年07月 [査読有り][通常論文]
The hypothesis that hermit crabs modify their shell-size preference according to their prospective growth rate was examined in the hermit crab Pagurus middendorffi. A simple model predicts that individuals should select larger shells when (1) shell availability is limited, (2) they approach moulting and (3) they will have a large increase in size at the next moult. In experiments, selected shell size decreased with the duration of the moult, and increased with increasing growth, supporting predictions 2 and 3. (C) 1997 The Association for the Study of Animal Behaviour. - Wada, S, M. Ashidate, S. GoshimaCrustacean Research 26 56 - 61 日本甲殻類学会 1997年 [査読有り][通常論文]
The reproductive behavior of the spiny king crab, Paralithodes brevipes, was observed in the laboratory. Females always molted before mating and extruding eggs. Males performed pre-copulatory guarding behavior before and/or after its mate molted. When males guarded females, prior to the female molting, the average duration from the start of guarding to molting was 38.6 ± 24.9SD hours. Females spawned within 24 hours of molting. Competition among males for females was observed, and larger males appeared to have a competitive advantage although copulation occurred even when males were smaller than their mates. - Goshima, S, S. Wada, H. OhmoriCrustacean Research 25 86 - 92 日本甲殻類学会 1996年 [査読有り][通常論文]
ごく最近,新種として記載されたヨモギホンヤドカリの分布と繁殖生態を,模式産地近くの函館湾葛登支の潮間帯において調べた.本種は潮間帯上部の潮線付近の転石域にパッチ状に分布し,季節的移動は見られない.4月から5月にかけて,雄が産卵直前の雌が入っている貝殻をはさみ持つ産卵前ガード行動が観察される.交尾・産卵直後にガード行動は終了する.抱卵雌は4月から2月の間に観察される.抱卵雌の出現時期とその後の卵の発達状態から,主な産卵期は5月で,雌は1年に1回産卵し,約9カ月間という長期にわたって抱卵することが明らかになった.交尾前ガード行動はホンヤドカリ属に普通に見られる行動であるが,長期にわたる抱卵期間は同地に生息する同属他種,あるいは他所に分布する同属のそれと比較しても非常に長く,きわだった繁殖特性といえる.このことは本種の属するホンヤドカリ属は,種類数の豊富さとともに,その繁殖特性にも多様な面が含まれることを示唆している. - Wada, S, T. Sonoda, S. GoshimaCrustacean Research 25 158 - 164 日本甲殻類学会 1996年 [査読有り][通常論文]
テナガホンヤドカリPagurus middendorffiiを用いて,1繁殖シーズン内で交尾前ガードに参加している雌雄の体サイズの時間変動について調べ,また,大型雄の配偶者をめぐる競争での有利性を実験室内での実験で検証した.その結果,大型雄は配偶者をめぐる競争で有利であることが明かとなった.また,繁殖シーズンを通して採集されたガード中の雌雄の体サイズ間でサイズ同類交配の傾向がみられた.サイズ同類交配の傾向は繁殖シーズンのピーク期,後期においても見られたが,前期には見られなかった.雌雄ともに交尾個体の体サイズは繁殖シーズンの前期から後期にかけて小さくなり,その理由として,雄に関しては現在と将来の繁殖成功度間のトレードオフ,あるいは生理的な制約が示唆され,雌では,繁殖と成長の配分のサイズ依存的な変異,あるいは小型個体に働く生理的な制約が考えられた. - Goshima, S, K. Ito, S. Wada, M. Shimizu, S. NakaoCrustacean Research 24 8 - 18 1995年 [査読有り][通常論文]
- Wada, S, S. Goshima, S. NakaoCrustacean Research 24 23 - 32 日本甲殻類学会 1995年 [査読有り][通常論文]
1992年から1994年まで北海道函館湾西岸に位置する葛登支岬の潮間帯においてテナガホンヤドカリPagurus middendorffiiの繁殖生態を調査した.交尾前ガードを行なっている個体は, 10月下旬から12月上旬にかけて観察され,11月上旬が最盛期であった.抱卵雌は10月から3月にかけて出現し,12月から2月にかけて,抱卵率は平均91.3%という高い値を示した.新規加入群と思われる性の判別ができなかった小型個体は4月から採集された.抱卵雌が全てのサイズクラスで高い割合で出現し,さらに,雌の抱卵していた卵が,個体群内で同調して発達していたことから,本種の雌が着底後1年で成熟し,その後,年に1回産卵していることが強く示唆された. - Ohmori, H, S. Wada, S. Goshima, S. NakaoCrustacean Research 24 85 - 92 日本甲殻類学会 1995年 [査読有り][通常論文]
函館湾葛登支岬の潮間帯転石城において,ホンヤドカリの貝殻利用状況と貝殻資源量について調査を行った.コドラート採集の結果,巻貝の出現頻度に比べクロスジムシロガイとタマキビガイを利用している個体の割合が有意に高いことがわかった.ヤドカリの貝殻の種類に対する選好性実験では,クロスジムシロガイを最も好んでいることから,貝殻の種類に対する選好性が貝殻利用状況に影響を与える1つの要因となっていることが示唆された.採集された個体の貝殻サイズの適合度(SAI)はヤドカリのサイズの増加に伴って減少する傾向が認められた.貝殻の種類別にSAIと貝殻資源量との関係についてみると,貝殻資源量が最も多いと思われるサイズの個体は比較的適した大きさの貝殻(SAI=1)を持っており,それより大きい個体ではSAIは1より小さく,それよりも小さい個体ではSAIは1より大きい値となることが明らかになった.すべての個体についてみると,いずれの種類の貝殻を利用している個体も比較的通した貝殻を利用していた.ヤドカリサイズの増加に伴って利用している貝殻の種類が変化していたことから,貝殻の種類を変えることによって,全体としては比較的高いSAIを維持していることが示唆された.
MISC
- 和田哲, 守田安祐美, 石原(安田)千晶 海洋と生物 40 (1) 106 -113 2018年02月15日 [査読無し][通常論文]
- 松政 正俊, 倉田 健悟, 和田 哲, グライガー マーク・J 日本ベントス学会誌 = Japanese journal of benthology 65 (1) 27 -27 2010年07月23日 [査読無し][通常論文]
- 五嶋 聖治, 和田 哲, 今井 一郎, 山口 篤 日本プランクトン学会報 57 (1) 56 -57 2010年02月26日 [査読無し][通常論文]
- TAKESHITA Fumio, HENMI Yasuhisa, WADA Satoshi 日本甲殻類学会大会講演要旨集 47th 136 2009年 [査読無し][通常論文]
- YASUDA Chiaki, SUZUKI Yutaro, WADA Satoshi 日本甲殻類学会大会講演要旨集 47th 45 2009年 [査読無し][通常論文]
- 和田 哲 Cancer : 会員連絡誌 0 (5) 33 -34 1996年05月01日 [査読無し][通常論文]
書籍等出版物
- 日本ベントス学会 (担当:分担執筆範囲:第６章 個体群動態)
海文堂出版 2020年09月 (ISBN: 9784303800512) viii, 246p - 日本ベントス学会 (担当:分担執筆範囲:第３章 種内変異と種内関係)
海文堂出版 2020年09月 (ISBN: 9784303800512) viii, 246p - 海に魅せられた北大の研究者たち (担当:分担執筆範囲:第６章 動物が好きな人へ)
海文堂出版 2018年08月 (ISBN: 9784303800017) 127p
Works（作品等）
- LASBOS Moodle 和田 哲 2021年05月 - 現在
- LASBOS Moodle 和田 哲 2020年10月 - 現在
- LASBOS Moodle 和田 哲 2020年08月 - 現在
- LASBOS Moodle 和田 哲 2020年08月 - 現在
- LASBOS Moodle 和田 哲 2020年04月 - 現在
共同研究・競争的資金等の研究課題
- 日本学術振興会：科学研究費助成事業研究期間 : 2024年04月 -2028年03月代表者 : 遊佐 陽一, 山口 幸, 關野 正志, 和田 哲, 豊田 賢治
- 日本学術振興会：科学研究費助成事業 基盤研究(C)研究期間 : 2021年04月 -2025年03月代表者 : 和田 哲在来種が外来種に示す適応進化は「進化トラップ (外来種に対する適応が、外来種がいない環境で不利にはたらく現象)」となる危険性がある。進化トラップは、陸上生物で危険性が指摘されているが、海洋動物でも作用する可能性がある。とくに肉食性巻貝の多くの種は浮遊幼生期をもたないため、個体群ごとで特殊な適応進化が生じやすい。本研究では、肉食性巻貝ヒメエゾボラと外来種ムラサキイガイに注目して、進化トラップ仮説を検証する。 2021年度は、1980年代における餌種がおもにムラサキイガイであったことが報告されている有珠湾で、摂餌状況の調査を行い、ムラサキイガイが分布していない函館湾葛登支岬周辺の海岸における調査結果と比較した。函館湾ではヒメエゾボラが巻貝を中心に摂餌していたのに対して、有珠湾における主な餌種は二枚貝であった。また、函館湾では餌を各個体が独占して摂食していたのに対して、有珠湾では、複数個体が１個体の餌を同時に摂食する状況が高頻度で観察された。 有珠湾で摂食されていた二枚貝は、函館湾で摂食されていた二枚貝よりも大きく、複数個体が同時に摂食していた二枚貝は、そのなかでも大型の餌であった。また、有珠湾のヒメエゾボラの平均サイズは函館湾よりも大型であることなどが確認された。 有珠湾における主な餌種が、すでにムラサキイガイから他の二枚貝に変化していたことは想定外であった。しかし、摂餌生態の明瞭な個体群間変異が認められた。また、複数個体が同時に摂食する行動は、単体で生息するアサリを餌としている現状では非適応的な行動だと考えられるが、群生するムラサキイガイを餌種としていた場合に有効な摂餌戦略であると考えられる。すなわち、有珠湾のヒメエゾボラには、すでに進化トラップが作用している可能性がある。
- 文部科学省：科学研究費補助金(基盤研究(C))研究期間 : 2013年 -2015年代表者 : 和田 哲ホンヤドカリ属のオスに見られる配偶者選択について「オスは他個体との遭遇を社会情報として利用して配偶者選択する」という仮説と「オスは他個体との遭遇を、その他個体に関する独自情報として利用して配偶者選択する」という仮説を検証した。研究の結果、オスがメスとの遭遇頻度を、そのメスに対する独自情報として利用し、他のオスによってガードされているという社会情報が配偶者選択に影響を与えることなどが明らかとなった。
- 文部科学省：科学研究費補助金(基盤研究(C))研究期間 : 2007年 -2009年代表者 : 和田 哲ホンヤドカリ属を対象として、オスとメスの成長と繁殖の資源配分様式を調べた。本属の一部の種では、交尾直前にメスが脱皮することがあり、繁殖期中にも成長する。本研究の結果、脱皮する個体は、とくに産卵間隔が長い傾向が強く、抱卵数も変異が大きかった。オスも配偶行動によって摂餌行動が抑制されるため、繁殖に費やす時間の増加が成長を低下させることが示唆されたが、実験ではそれを強く支持する結果は得られなかった。
- 文部科学省：科学研究費補助金(若手研究(B))研究期間 : 2005年 -2006年代表者 : 和田 哲ホンヤドカリ属における成長と繁殖の資源配分パターンと環境条件の影響を明らかにするために、函館湾に生息するホンヤドカリ、イクビホンヤドカリ、ケアシホンヤドカリ、ヨモギホンヤドカリのガードペアを採集後、産卵まで飼育して、産卵間隔、産卵数、交尾直前脱皮の有無、メスサイズ、貝殻サイズの関係を調べた。その結果、1回産卵/年であるヨモギホンヤドカリのメスは、全て脱皮したが、複数回産卵/年の他種個体群のメスで、産卵間隔の長い個体のほうが高頻度で脱皮する傾向が得られた。いっぽう、産卵数やメスサイズ、貝殻サイズの影響は、種間で異なっていた。またホンヤドカリでは、脱皮頻度と産卵間隔の時間変動が大きく、本種の成長と繁殖における資源配分が水温や餌条件などの環境条件によって大きく左右されることが示唆された。なお、今年度は飼育実験によって、これらの環境条件の影響を検証する予定だったが、飼育環境に不備があり、多くの飼育個体が死亡したために、検証を行うことができなかった。また、函館湾のヨモギホンヤドカリを対象種として、野外で採集された個体を3日間飼育して、脱皮個体数と脱皮あたり成長量を測定して、成長フェノロジーを調査した。その結果、ヨモギホンヤドカリでは、夏季に脱皮頻度が大きく低下する傾向が得られた。この傾向は、夏季に脱皮頻度が高い同属他種とは大きく異なっているため、本種と他種における成長と繁殖の資源配分の違いにも大きく関与する可能性が示唆された。
- 文部科学省：科学研究費補助金(若手研究(B))研究期間 : 2003年 -2004年代表者 : 和田 哲ヤドカリには交尾・産卵直前に雌が(1)常に脱皮する種、(2)脱皮しない種、(3)脱皮したりしなかったりする種がいる。(2)や(3)に属する種の存在は、脱皮がヤドカリの配偶行動に不可欠ではないことを示唆する。しかし多くの種で雌は交尾直前に脱皮する。本研究は交尾直前脱皮の適応的意義の解明を目的としておこなった。上記(3)に属する種では、同一個体群の雌が連続産卵雌(過去に産卵した卵を孵化した雌がすぐに雄と交尾し産卵する)と不連続産卵雌(過去の卵を持たない雌が産卵する)に区分できる。本研究はこの点に着目して以下の仮説を検証した。成長仮説:雌は脱皮のコストで不連続産卵となっても、成長するために脱皮する繁殖仮説:脱皮が抱卵場所の更新に役立つならば、雌は連続産卵時に脱皮する上記(3)に属し高知県で普通に見られるホンヤドカリ属3種(ホンヤドカリ、クロシマホンヤドカリ、ユビナガホンヤドカリ)を対象種として、野外で雄に交尾前ガードされている雌をペアとして採集し、研究室で産卵まで飼育して、連続/不連続産卵の識別と脱皮の有無等を比較した。その結果、全ての種で成長仮説が支持された。さらにユビナガホンヤドカリを用いて、脱卵数、抱卵数、オスとメスの体サイズ、メスが背負っている貝殻サイズが脱皮頻度に与える影響を訥べた結果、脱皮によって脱卵数が増加し抱卵数が減少する傾向を認められた。また、脱皮あたり成長率は有意に0よりも大きく、脱皮によって体サイズが増大することが明らかとなった。以上の結果でも成長仮説が支持された。ホンヤドカリ属の他種を含めた種間比較の結果、成長仮説はホンヤドカリ属における(1)-(3)の種間変異もよく説明することが示唆された。
- 文部科学省：科学研究費補助金(奨励研究(A), 若手研究(B))研究期間 : 2001年 -2002年代表者 : 和田 哲甲殻類では交尾(産卵)直前にメスが(1)常に脱皮する種、(2)常に脱皮しない種、(3)脱皮したりしなかったりする種がいる。これは甲殻類の生活史進化における興味深い現象だが、研究例はほとんどない。本研究ではヤドカリ類の生活史形質、とくにメスの交尾(産卵)直前脱皮と繁殖形質に着目して調査をおこなった。高知県中央部に位置する浦の内湾の転石海岸と高知県東部羽根岬に生息するホンヤドカリ、ユビナガホンヤドカリ、アカシマホンヤドカリ、カノコケアシホンヤドカリなどを対象として交尾直前脱皮の有無、脱皮当たり成長率、繁殖フェノロジー、産卵数、幼生艀化数を記録した。その結果、幼生艀化後すぐに新たな産卵をおこなう連続産卵メスよりも不連続産卵メスの方が交尾直前脱皮頻度が高く、この脱皮によって実質的な対サイズの増大が認められた。産卵パターン(連続か不連続か)や脱皮の有無による産卵数の違いは明らかではなかった。これらのことから、ヤドカリにとって交尾直前脱皮は繁殖成功度を高めるわけではなく、清澄を介して将来の生存率や繁殖力を高める機能をもつことが示唆された。さらに、脱皮と産卵の間にトレードオフ関係が成立していることが示唆された。しかし、ホンヤドカリとユビナガホンヤドカリを対象として、繁殖期を通して交尾直前脱皮と産卵パターンの関係を調べたところ、両種共に繁殖盛期に連続産卵メスの脱皮頻度が高くなった。このことは脱皮と産卵のトレードオフが単純な関係ではなく、水温や餌の質と量などの環境要因や産卵数などの内的要因の影響を受けていることを示唆している。
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