研究者情報

マスター

アカウント（マスター）

• 氏名

  岸田　治(キシダ　オサム), キシダ　オサム

所属（マスター）

• 北方生物圏フィールド科学センター　森林圏ステーション　和歌山研究林

所属（マスター）

• 北方生物圏フィールド科学センター　森林圏ステーション　和歌山研究林

独自項目

syllabus

• 2021, 森林圏科学特論Ⅲ, Advanced Course in Forest Sphere Science III (Conservation Biology), 修士課程, 環境科学院, 動物生態学，保全，野外調査，研究発表 Animal Ecology, Conservation, Field Investigation, Presentation
• 2021, 大学院共通授業科目（一般科目）：自然科学・応用科学, Inter-Graduate School Classes(General Subject):Natural and Applied Sciences, 修士課程, 大学院共通科目, 生態学、北方生態系、北海道、植物、動物、昆虫、魚類、森林、山岳、ツンドラ、沿岸、河川、湿原、相互作用、外来種、野生作物、気候変動 ecology, northern ecosystem, Hokkaido, plants, animals, insects, fishes, forest, mountain, tundra, seacoast, river, wetland, interaction, invasive species, field crop, climate change
• 2021, 北方生態系の生物多様性基礎論, Fundamental Course in Biodiversity of Northern Ecosystems, 修士課程, 環境科学院, 生態学、北方生態系、北海道、植物、動物、昆虫、魚類、森林、山岳、ツンドラ、沿岸、河川、湿原、相互作用、外来種、野生作物、気候変動 ecology, northern ecosystem, Hokkaido, plants, animals, insects, fishes, forest, mountain, tundra, seacoast, river, wetland, interaction, invasive species, field crop, climate change
• 2021, 動物生態学特論Ⅱ, Advanced Course in Animal Ecology II, 修士課程, 環境科学院, 動物、個体群、群集、行動、保全、進化、種間相互作用 Animal, population, community, behavior, conservation, evolution, species interaction
• 2021, 野生動物管理実習, Practical Field Work on Wildlife Conservation, 学士課程, 農学部, 野生動物調査，動物生態学，捕獲法，マーキング，群集解析，哺乳類，鳥類，魚類，昆虫類
• 2021, 野生動物管理学, Wildlife Management, 学士課程, 農学部, 保全, 群集, 個体群, 生物多様性, 進化，外来種種
• 2021, 森林空間機能学, Forest Influence, 学士課程, 農学部, 森林、環境保全機能、生物多様性保全、野生生物保全、土地利用、流域保全、森林利用
• 2021, 森林空間機能学演習, Seminar on Forest Influence, 学士課程, 農学部, 森林の種類と分布、森林空間、環境保全機能、森林保全、資料作成方法、発表方法、ディスカッション
• 2021, 一般教育演習(ﾌﾚｯｼｭﾏﾝｾﾐﾅｰ), Freshman Seminar, 学士課程, 全学教育, 生態学、観察実験、進化、食う―食われる関係、温暖化、リモートセンシング、樹木、両生類、昆虫、土壌、グループワーク
• 2021, 一般教育演習(ﾌﾚｯｼｭﾏﾝｾﾐﾅｰ), Freshman Seminar, 学士課程, 全学教育, 洞爺湖の環境、有珠山噴火、有珠山植生回復、海藻の生態、森林の生態

researchmap

プロフィール情報

学位

• 博士（水産科学）（北海道大学）

プロフィール情報

• 姓

  岸田, キシダ

• 名

  治, オサム

• ID各種

  200901011831844175

対象リソース

http://ok.fsc.hokudai.ac.jp/
http://ok.fsc.hokudai.ac.jp/en/

業績リスト

研究キーワード

• アズマヒキガエル   外来種   誘導防御   表現型可塑性   誘導攻撃   間接効果   生態系機能   形態変化   エゾサンショウウオ   適応   捕食   相互作用   エゾアカガエル   両生類   栄養カスケード   メソコスム   遺伝学   動物   生態学   個体群生態学   群集生態学   行動生態学   進化生態学   Community Ecology   Evolutionary Ecology   

研究分野

• ライフサイエンス / 生態学、環境学

経歴

• 2012年11月 - 現在 北海道大学 北方生物圏フィールド科学センター 准教授
• 2009年04月 - 2012年10月 北海道大学 北方生物圏フィールド科学センター 助教

受賞

• 2009年 第13回 日本生態学会宮地賞
  

論文

• A comparison of sex‐specific markers for two wild masu salmon populations in Hokkaido, Japan

  Takuya K. Hosoki, Noël M. Clark, Ryo Futamura, Senri Moriyama, Osamu Kishida, Yoichiro Kanno

  Aquaculture, Fish and Fisheries 4 4 2024年07月09日 

  Abstract We evaluated the utility of three male‐specific molecular markers, sdY, sdY 227U and OtY2m, in two wild populations of masu salmon (Oncorhynchus masou) in southwestern Hokkaido, Japan. Male‐specific fragments amplified in all phenotypic males across the markers. Phenotypic females were genetically identified as males using sdY (57%) and sdY 227U (4%), but no phenotypic females were identified as males using OtY2m. We conclude that OtY2m was the most reliable sex marker, followed closely by sdY 227U, among those tested in our study populations. Additional research is warranted to test the applicability of these markers in other populations and Oncorhynchus species.
• 北海道北部のブトカマベツ川におけるイトウParahucho perryiの生息環境特性

  遠藤 大斗, 宇野 裕美, 岸田 治, 森田 健太郎

  保全生態学研究 28 2 453 - 465 2023年12月 [査読有り]
  
• Aging Contrast: A Contrastive Learning Framework for Fish Re-identification Across Seasons and Years

  Weili Shi, Zhongliang Zhou, Benjamin H. Letcher, Nathaniel Hitt, Yoichiro Kanno, Ryo Futamura, Osamu Kishida, Kentaro Morita, Sheng Li

  Lecture Notes in Computer Science 252 - 264 2023年11月27日
• Proximate stimuli: An overlooked driving force for risk‐induced trait responses affecting interactions in aquatic ecosystems

  Hisanori Okamiya, Osamu Kishida

  Population Ecology 2022年02月08日
• Size-dependent growth tactics of a partially migratory fish before migration

  Ryo Futamura, Kentaro Morita, Yoichiro Kanno, Shoji Kumikawa, Yuichi Matsuoka, Atsushi Okuda, Hiroshi Sugiyama, Hiroyuki Takahashi, Jiro Uchida, Osamu Kishida

  Oecologia 2022年01月22日 [査読有り]
   

  In many migratory species, smaller migrants suffer higher mortality rates during the risky migration. To minimize the size-selective mortality, migrants with smaller body sizes would need to accelerate growth rates or delay migration timing to attain a large enough body size prior to migration. To test these predictions, we investigated size-dependent patterns of growth rates and migration timing of juvenile masu salmon (Oncorhynchus masou) before their oceanic migration. We tracked uniquely marked individuals in a study population consisted of oceanic migrants and river-dwelling residents using mark-recapture surveys and PIT-tag antenna-reader system. Data supported our predictions about size-dependent growth rates and migration timing. For approximately 6 months before outmigration (i.e., between the decision of migration and the start of migration), eventual migrants grew more than residents if their initial size was smaller, but such a difference in growth rate diminished for fish with larger initial sizes. In addition, smaller eventual migrants delayed the timing of outmigration compared to larger individuals, to attain a larger body size in the river prior to migration. These results suggest that size-selective mortality during migration has shaped size-dependent patterns of the pre-migration growth in migratory masu salmon. Size-conditional changes in growth rate and duration of pre-migration period may be an adaptive tactic for the migratory animals.
• Size-selective mortality occurs in smolts during a seaward migration, but not in river residents, in masu salmon (Oncorhynchus masou)

  Ryo Futamura, Kentaro Morita, Yoichiro Kanno, Osamu Kishida

  Environmental Biology of Fishes 105 12 1833 - 1843 2022年01月17日 [査読有り]
  
• Predators mitigate the destabilising effects of heatwaves on multitrophic stream communities

  Samuel R. P.‐J. Ross, Jorge García Molinos, Atsushi Okuda, Jackson Johnstone, Keisuke Atsumi, Ryo Futamura, Maureen A. Williams, Yuichi Matsuoka, Jiro Uchida, Shoji Kumikawa, Hiroshi Sugiyama, Osamu Kishida, Ian Donohue

  Global Change Biology 28 2 403 - 416 2022年01月 [査読有り]
   

  Amidst the global extinction crisis, climate change will expose ecosystems to more frequent and intense extreme climatic events, such as heatwaves. Yet, whether predator species loss-a prevailing characteristic of the extinction crisis-will exacerbate the ecological consequences of extreme climatic events remains largely unknown. Here, we show that the loss of predator species can interact with heatwaves to moderate the compositional stability of ecosystems. We exposed multitrophic stream communities, with and without a dominant predator species, to realistic current and future heatwaves and found that heatwaves destabilised algal communities by homogenising them in space. However, this happened only when the predator was absent. Additional heatwave impacts on multiple aspects of stream communities, including changes to the structure of algal and macroinvertebrate communities, as well as total algal biomass and its temporal variability, were not apparent during heatwaves and emerged only after the heatwaves had passed. Taken together, our results suggest that the ecological consequences of heatwaves can amplify over time as their impacts propagate through biological interaction networks, but the presence of predators can help to buffer such impacts. These findings underscore the importance of conserving trophic structure, and highlight the potential for species extinctions to amplify the effects of climate change and extreme events.
• Occurrence of mature male white-spotted charr (Salvelinus leucomaenis) in spring, an unusual season

  Ryo Futamura, Kentaro Morita, Koume Araki, Masato Ayumi, Shoji Kumikawa, Yuichi Matsuoka, Atsushi Okuda, Hiroshi Sugiyama, Hiroyuki Takahashi, Taro Takahashi, Jiro Uchida, Osamu Kishida

  Ichthyological Research 69 1 194 - 196 2022年01月
• Utilizing environmental DNA for wide-range distributions of reproductive area of an invasive terrestrial toad in Ishikari river basin in Japan

  Hiroki Mizumoto, Osamu Kishida, Kotaro Takai, Naru Matsuura, Hitoshi Araki

  Biological Invasions 24 4 1199 - 1211 2021年12月15日 [査読有り]
   

  Understanding the distribution of invasive species and their reproductive area is crucial for their managements after invasion. While catch and observation surveys are still embraced, environmental DNA (eDNA) has been increasingly utilized as an efficient tool for identifying these species in the wild. In this study, we developed a Bufo-specific eDNA assay for detecting an invasive, toxic, and terrestrial toad species Bufo japonicus formosus in Hokkaido, Japan, and applied it to their reproductive area at watershed scale. The eDNA assay was field-validated in ponds where B. japonicus were observed, as well as in rivers downstream of the reproductive ponds. Thus, the assay provided us an opportunity to screen watersheds that include their reproductive area by collecting downstream water samples. Applying it to the Ishikari river basin, the largest river basin in Hokkaido (c.a., 14,330 km²), we detected toad eDNA at 32 out of 73 sampling sites. They are composed of eleven sites with species observation records nearby (all the sites with observation records within a 500 m radius) and 21 sites without such records. And those eDNA detections were from twelve out of 31 river systems in the entire river basin. A Bayesian, multiscale occupancy model supported high eDNA detectability among those sites. These results suggest that the eDNA assay can efficiently estimate the presence of reproductive area of the terrestrial toad even from a distant downstream of the watershed, and that it provides a powerful means of detecting new reproductive area and monitoring further spread of invasive species.
• Spatially variable hydrological and biological processes shape diverse post‐flood aquatic communities

  Hiromi Uno, Mizushi Yokoi, Keitaro Fukushima, Yoichiro Kanno, Osamu Kishida, Wataru Mamiya, Rei Sakai, Shunsuke Utsumi

  Freshwater Biology 67 3 549 - 563 2021年12月09日 [査読有り]
   

  Diverse aquatic environments in floodplains support high biodiversity, including plankton, benthos, nekton (fish), and amphibians. Variation in aquatic communities among waterbodies should be explained not only by the spatial variation in the environment at low flow but also by the hydrological dynamics and biological responses over flood and recession periods. However, very few studies have examined the formation processes of floodplain aquatic communities over flood periods. In this study, we aimed to obtain a mechanistic understanding of the assembly of aquatic communities on a temperate floodplain by conducting intensive fieldwork during and after seasonal flooding. The study was conducted in the Butokamabetsu River catchment in northern Hokkaido, where snowmelt causes annual spring floods. At peak flow, floodwater not only flow through main stream river and the extant side channels, but also flow through some palaeo-side channels, which are usually isolated from the mainstream river and harbour stagnant water. As the floods recede, palaeo-side channels become isolated from the mainstream river and their flow cease, but the timing of the flow cessation varied among palaeo-side channels. We hypothesised that this spatial asynchrony in the timing of flow cessations shapes diverse floodplain aquatic communities. Therefore, we conducted field surveys of four faunal groups (plankton, benthos, nekton [fish], and amphibian) during and after the spring flood in 2019. The post-flood aquatic communities varied spatially, according to the flow at peak flood, the timing of flow cessation, and the flow at low flow. Plankton composition was influenced by the water flow at peak flood, and they were more abundant in waterbodies that were never flushed by floodwaters. Fish composition was also influenced by the water flow at peak flood; in particular, salmonids were more abundant in waterbodies that were hydrologically connected to the main stream at peak flood. The presence of amphibian eggs was influenced by the timing of flow cessation; eggs were laid in waterbodies with stagnant water during breeding season. The benthic composition was influenced by flow at low flow. After the flood had receded, these different distribution patterns of the four biological groups led to gradual variation of aquatic communities among waterbodies on a floodplain. Overall, this study showed that hydrological dynamics during flood recession shapes the post-flood aquatic communities, and the spatial variability in the hydrological dynamics and the different responses of the four faunal groups support diverse aquatic communities on a floodplain. Importance of the natural geomorphological complexities, where paleo-side channels with wide range of hydrological connectivity to the river channel co-occur, as well as the natural hydrological dynamics of snowmelt recession, where the flooding discharge gradually decrease over a certain period in spring for floodplain aquatic communities are highlighted.
• Paedomorphosis in the Ezo salamander (Hynobius retardatus) rediscovered after almost 90 years

  Hisanori Okamiya, Ryohei Sugime, Chiharu Furusawa, Yoshihiro Inoue, Osamu Kishida

  Zoological Letters 7 14 2021年12月 [査読有り]
   

  Although paedomorphosis is widespread across salamander families, only two species have ever been documented to exhibit paedomorphosis in Hynobiidae. One of these two exceptional species is Hynobius retardatus in which paedomorphosis was first reported in 1924, in specimens from Lake Kuttara in Hokkaido. This population became extinct after the last observation in 1932; since then, no paedomorphs of this species have been reported anywhere. Here, we report the rediscovery of paedomorphs of this species. Three paedomorph-like male salamanders were collected from a pond in the south Hokkaido in December 2020 and April 2021; in size, these specimens were similar to metamorphosed adults but they still displayed larval features such as external gills and a well-developed caudal fin. An artificial fertilization experiment demonstrated that they were sexually compatible with metamorphosed females, thus, confirming them to be paedomorphs. Future efforts to find additional paedomorphs in this and other populations are required to assess the prevalence of paedomorphosis in H. retardatus and to improve understanding of the ecology and evolution of paedomorphisis in Urodela.
• Are toxic effects of alien species affected by their prey? Evaluation by bioassay with captive-bred toad embryos and a vulnerable predator

  Hisanori Okamiya, Masataka Tagami, Michael Crossland, Osamu Kishida

  Hydrobiologia 848 19 4445 - 4452 2021年11月 [査読有り]
  
• Complex effects of body length and condition on within‐tributary movement and emigration in stream salmonids

  Yoichiro Kanno, Audrey C. Harris, Osamu Kishida, Shunsuke Utsumi, Hiromi Uno

  Ecology of Freshwater Fish 2021年09月04日 [査読有り]
   

  Movement patterns of stream fish vary individually, but little is known about how a set of individual characteristics affect movement at multiple spatial scales. We investigated the effect of body length and condition (i.e. weight relative to length) on emigration from a tributary and movement within the tributary during summer in Japanese salmonids (white-spotted charr Salvelinus leucomaenis and masu salmon Oncorhynchus masou) using mark-recapture and PIT antenna technology. Emigration from the tributary was influenced more strongly by body length than by body condition, whereas movement within the tributary (> 20 m) was influenced by body condition and their interaction with body length. Specifically, larger individuals in better body condition were more likely to stay locally (<= 20 m), but smaller individuals in better condition were more likely to move in the tributary. We discuss benefits and costs of movement that vary with individual characteristics (i.e. body length and condition) and spatial scales. In one instance (charr between June and July), survival rates were lower in smaller individuals, which also were more likely to emigrate from the tributary, suggesting that emigration might have been facilitated by the mortality cost of staying in the tributary. This study indicates that stream fish movement is shaped by complex mechanisms that differ by spatial scale. Although complex, two study species often responded similarly, indicative of emerging regularities across species in determinants of multi-scale stream fish movement.
• Native frogs ( Rana pirica ) do not respond adaptively to alien toads ( Bufo japonicus formosus ) 100 years after introduction

  Hisanori Okamiya, Yoshihiro Inoue, Kotaro Takai, Michael R. Crossland, Osamu Kishida

  Ecological Research 2021年08月30日 [査読有り]
  
• Hatch timing of two subarctic salmonids in a stream network estimated by otolith increments

  Kevin A. Fitzgerald, Matt R. Haworth, Kevin R. Bestgen, Collin J. Farrell, Shunsuke Utsumi, Osamu Kishida, Hiromi Uno, Yoichiro Kanno

  Fisheries Management and Ecology 28 6 507 - 515 2021年06月29日 [査読有り]
   

  Hatch timing in autumn-spawning stream salmonids is poorly understood in the subarctic region because snow cover prevents direct sampling of cryptic early life stages. Otolith micro-increment analysis was used to infer hatch dates of white-spotted charr Salvelinus leucomaenis (Pallas) and masu salmon Oncorhynchus masou (Brevoort) in a mainstem-tributary network in northern Japan. Accuracy and precision were validated by ageing hatchery individuals with known hatch date ranges. In July 2018, 93 wild young-of-the-year white-spotted charr and 81 masu salmon were collected and aged. Masu salmon hatched, on average, 24 days earlier (mean = February 8) than white-spotted charr (March 4), and hatch dates spanned a minimum of 2 months for each species. In masu salmon, hatch dates of individuals collected in the mainstem were nearly 3 weeks earlier than those in a tributary. This study provided knowledge on intra- and inter-specific variation in hatch timing of native salmonids in a subarctic stream network.
• The Japanese Common Toad, Bufo japonicus formosus, Contains Toxin in the Egg Stage

  Hisanori Okamiya, Kotaro Takai, Osamu Kishida

  Current Herpetology 40 1 2021年03月02日 [査読有り]
  
• Demography and productivity during the recovery time sequence of a wild edible bamboo after large-scale anthropogenic disturbance

  Noboru Katayama, Osamu Kishida, Chikako Miyoshi, Shintaro Hayakashi, Kinya Ito, Rei Sakai, Aiko Naniwa, Hiroyuki Takahashi, Kentaro Takagi

  PLOS ONE 15 12 e0243089 - e0243089 2020年12月01日 [査読有り]
   

  Anthropogenic disturbances in forest management practices can affect wild edible plants. Soil scarification is a large-scale disturbance that may cause long-term reduction in productivity of edible dwarf bamboo, Sasa kurilensis, in northern Japan. For their effective and sustainable use, we need to understand the recovery process after such disturbances. At 14 study sites in the Teshio Experimental Forest of Hokkaido University where soil scarification had been conducted between 2 and 44 years prior, the number and stem diameter of old and young (newly emerged, edible) culms was recorded. At sites that were within 11 years of soil scarification, the proportion of old culms (<11%) was lower than in the control area where soil scarification had never been conducted. At sites where more than 15 years had passed since soil scarification, the relative number of old culms was nearly equal to that in control area. Additionally, the number of young culms increased with an increasing number of old culms. These results suggest that recovery of productivity (in term of number) of edible culms may take a few decades. In contrast, the culm diameter of young culms increased linearly with time since soil scarification, but the 95% confidence interval in this relationship suggests that dwarf bamboo can produce thick edible culms soon after soil scarification. These findings will provide useful insights into how to obtain high quality bamboo culms following anthropogenic disturbances in future.
• Expression of Genes Involved in Offensive and Defensive Phenotype Induction in the Pituitary Gland of the Hokkaido Salamander (Hynobius retardatus)

  Masatoshi Matsunami, Toru Miura, Osamu Kishida, Hirofumi Michimae, Kinya Nishimura

  Zoological Science 37 6 2020年10月12日 [査読有り]
  
• Enhanced recruitment of larger predators in the presence of large prey

  Kunio Takatsu, Osamu Kishida

  Journal of Animal Ecology 89 7 1615 - 1627 2020年07月 [査読有り]
  
• A multistate mark–recapture approach to characterize stream fish movement at multiple spatial scales

  Yoichiro Kanno, Naoki Yui, Wataru Mamiya, Rei Sakai, Yuri Yabuhara, Tohru Miyazaki, Shunsuke Utsumi, Osamu Kishida, Hiromi Uno

  Canadian Journal of Fisheries and Aquatic Sciences 77 6 1090 - 1100 2020年06月 [査読有り]
   

  We studied movement of a native salmonid, white-spotted char (Salvelinus leucomaenis), in a 1-km tributary in northern Hokkaido, Japan, in May–July 2018. Based on physical mark–recapture of 501 unique individuals and detection by mobile PIT antenna over monthly intervals, a majority of fish (70%–80%) stayed within 60 m of previously released locations, demonstrating what appeared to be restricted movement patterns. However, fixed PIT antenna data showed that as much as 17% of marked individuals emigrated from the study area during the 2-month study period. Probability of emigration did not depend on where in the 1-km segment individuals had been released, indicating that emigration likely represented long-distance movement. Once emigrants made a decision to emigrate, they left the tributary within 1–3 median days by moving downstream in a unidirectional manner, based on detections at a total of three antenna arrays deployed throughout the tributary. Our multiscale analysis provided strong support for co-existence of short- and long-distance movement patterns, and we conclude that movement data at multiple spatial scales complement each other to characterize population-scale movement.
• Prospective interspecies interaction between Siberian and Ezo salamander larvae

  Keisuke Atsumi, Osamu Kishida

  Ecological Research 35 3 533 - 539 2020年05月 [査読有り]
  
• Host phenologies and the life history of horsehair worms (Nematomorpha, Gordiida) in a mountain stream in northern Japan

  Nanoko Meguro, Osamu Kishida, Shunsuke Utsumi, Shigeru Niwa, Susumu Igarashi, Chikara Kozuka, Aiko Naniwa, Takuya Sato

  Ecological Research 35 3 482 - 493 2020年05月 [査読有り][通常論文]
  
• Comparison of susceptibility to a toxic alien toad (Bufo japonicus formosus) between predators in its native and invaded ranges

  Narumi Oyake, Nayuta Sasaki, Aya Yamaguchi, Hiroyuki Fujita, Masataka Tagami, Koki Ikeya, Masaki Takagi, Makoto Kobayashi, Harue Abe, Osamu Kishida

  FRESHWATER BIOLOGY 65 2 240 - 252 2020年02月 [査読有り][通常論文]
   

  To manage biological invasions effectively, the impacts of alien species on the demography and traits of native species must be known, but determining those impacts can be challenging. We used a comparative approach to gain insight into the impacts that an alien toad (Bufo japonicus formosus) might have on native Japanese predatory amphibians. We compared the susceptibility of native predator species to alien toad toxins in the alien-invaded range and the susceptibility of closely related native predator species to the toxins in the alien toad's native range to investigate the impacts of an alien on a native species. Bufo japonicus formosus is native to Honshu, but was recently introduced to Hokkaido and Sado. In laboratory experiments, we compared individual mortality of predators exposed to a toad hatchling between novel predators on the toad-invaded islands and ecologically similar congeneric or conspecific species on Honshu, where the toad is native. We also compared (1) the percentage of individuals that consumed a toad hatchling and (2) toxin resistance (i.e. survival and growth of individuals after toad consumption) between these two groups of predators, as mechanistic components behind the susceptibility of the predators to the toxic prey. The mortality of Rana pirica from all populations after consumption of a toad hatchling was almost 100%, and that of Hynobius retardatus ranged from 14 to 90%, depending on the population. In contrast, the mortality of Rana ornativentris and Hynobius nigrescens was near 0% regardless of population. These differences between congeneric predators were mostly due to differences in their toxin resistance. These results suggest that the alien toad is a potential threat to the novel amphibian predators on Hokkaido, although they also imply that the novel predators on Hokkaido have the potential to develop toxin resistance through adaptive evolution. However, this counteradaptation may have a higher chance of evolving in H. retardatus than in R. pirica because of differences in their genetic backgrounds.
• Visual preference of males for conspecific mates in mutually ornamented fish: possible support for the species recognition hypothesis

  Atsumi Keisuke, Kishida Osamu, Koizum Itsuro

  JOURNAL OF ETHOLOGY 37 3 353 - 362 2019年09月 [査読有り][通常論文]
  
• Long-term fauna and flora records of the experimental forests of the Forest Research Station of Hokkaido University, Japan

  Terada, Chisato, Kwon, TaeOh, Kazahari, Nobuko, Kishida, Osamu, Utsumi, Shunsuke

  ECOLOGICAL RESEARCH 34 3 349 - 349 2019年05月 [査読有り][通常論文]
   

  The Forest Research Station of Hokkaido University owns a vast area of experimental forests, which are composed of a large variety of ecosystems ranging from aquatic ecosystems, such as wetlands and river basins, to various types of forests, such as primary, secondary and artificial forests. Additionally, these forests are representative of numerous climatic zones, such as warm temperate, cool temperate and subarctic. Since the initial establishment of the Forest Research Station in 1901, huge efforts have been devoted to recording the vegetation structure and vertebrate assemblages of these experimental forests. Thus, a large body of literature and long-term data on fauna and flora of these forests has been accumulated in our archives. However, most of these records have been written in Japanese and are not opened to the public or well structured. Therefore, we comprehensively reviewed these records and related scientific articles from the 1910s to the 2010s to build up the database for vascular plant and vertebrate animals that inhabited (in the past) and/or are currently inhabiting in the experimental forests. Additional site-specific information was also listed, including geological and topographical characteristics where species were found as well as the localities, survey area and year in which species were recorded. These databases, which span a large temporal and spatial scale, are expected to provide useful data for research or educational purposes and for understanding the flora and fauna of Japan. These can also contribute to a greater understanding of the historical transition of biodiversity in Japan.
• Foraging traits of native predators determine their vulnerability to a toxic alien prey

  Kazila Evangelia, Osamu Kishida

  FRESHWATER BIOLOGY 64 1 56 - 70 2019年01月 [査読有り][通常論文]
  
• Environmental DNA enables detection of terrestrial mammals from forest pond water

  Masayuki Ushio, Hisato Fukuda, Toshiki Inoue, Kobayashi Makoto, Osamu Kishida, Keiichi Sato, Koichi Murata, Masato Nikaido, Tetsuya Sado, Yukuto Sato, Masamichi Takeshita, Wataru Iwasaki, Hiroki Yamanaka, Michio Kondoh, Masaki Miya

  MOLECULAR ECOLOGY RESOURCES 17 6 e63 - e75 2017年11月 [査読有り][通常論文]
   

  Terrestrial animals must have frequent contact with water to survive, implying that environmental DNA (eDNA) originating from those animals should be detectable from places containing water in terrestrial ecosystems. Aiming to detect the presence of terrestrial mammals using forest water samples, we applied a set of universal PCR primers (MiMammal, a modified version of fish universal primers) for metabarcoding mammalian eDNA. The versatility of MiMammal primers was tested in silico and by amplifying DNAs extracted from tissues. The results suggested that MiMammal primers are capable of amplifying and distinguishing a diverse group of mammalian species. In addition, analyses of water samples from zoo cages of mammals with known species composition suggested that MiMammal primers could successfully detect mammalian species from water samples in the field. Then, we performed an experiment to detect mammals from natural ecosystems by collecting five 500-ml water samples from ponds in two cool-temperate forests in Hokkaido, northern Japan. MiMammal amplicon libraries were constructed using eDNA extracted from water samples, and sequences generated by Illumina MiSeq were subjected to data processing and taxonomic assignment. We thereby detected multiple species of mammals common to the sampling areas, including deer (Cervus nippon), mouse (Mus musculus), vole (Myodes rufocanus), raccoon (Procyon lotor), rat (Rattus norvegicus) and shrew (Sorex unguiculatus). Many previous applications of the eDNA metabarcoding approach have been limited to aquatic/semiaquatic systems, but the results presented here show that the approach is also promising even for forest mammal biodiversity surveys.
• Giant cannibals drive selection for inducible defence in heterospecific prey

  Kunio Takatsu, Volker H. W. Rudolf, Osamu Kishida

  BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY 120 3 675 - 684 2017年03月 [査読有り][通常論文]
   

  Predation can strongly influence the evolution of prey species by selecting for defensive phenotypes that reduce the risk of predation. Although cannibalism is frequent in predators and is known to strongly influence predator-prey dynamics, it is largely neglected when studying the evolution of phenotypic defences in prey. Changes in cannibalism can alter the abundance, size-structure, and even phenotypes within predator populations, and thereby change the numerical and per-capita effects driving the selection pressure on defensive phenotypes in prey. In the present study, we experimentally manipulated the presence and absence of cannibalism in predatory salamander larvae Hynobius retardatus (Dunn) and examined how this affects the expression of and selection pressure on inducible defensive phenotype (bulgy phenotype) in its prey, Rana pirica (Matsui) tadpoles. In the absence of cannibalism, salamanders were generally not sufficiently large to consume tadpoles, tadpoles did not express the defensive phenotype, and all phenotypes had equally high survival. By contrast, cannibalism of salamanders accelerated growth rates, leading to the development of 'giant' cannibalistic morphs that were able to consume tadpoles. Importantly, only in the presence of these giant cannibals did tadpoles express a defensive 'bulgy' phenotype that had significantly higher survival rates than phenotypes without this defence, indicating that cannibalism altered the selective regime for defensive traits in prey. The results of the present study demonstrate that cannibalism can drive trait evolution in predator-prey systems and suggest that we cannot predict how changes in numerical effects in predator populations affect selection regimes on prey traits without accounting for concurrent changes in predator per-capita effects. (C) 2016 The Linnean Society of London.
• Soldiers with large weapons behave aggressively against predators: correlated morphological and behavioral defensive traits in a eusocial aphid

  Mitsuru Hattori, Osamu Kishida, Takao Itino

  INSECTES SOCIAUX 64 1 39 - 44 2017年02月 [査読有り][通常論文]
   

  In social insects, intracaste variation suggests the existence of adaptive mechanisms such as polymorphism and polyphenism (i.e., subcastes) for maintaining the sophisticated social system. Here, we investigated intracaste variation patterns of a behavior (i.e., aggressiveness) and of morphology in the soldier caste of a eusocial aphid, Ceratovacuna japonica (Homoptera, Hormaphidinae). This species produces sterile individuals (soldiers), which have larger horns and forelegs than non-soldier reproductive individuals and which specialize in colony defense against predators. We previously showed that in midsummer, when predators are abundant, mother aphids produce soldiers with larger horns and forelegs than they do in early summer, when predators are few. However, the aggressiveness of C. japonica soldiers, another functional trait for colony defense, has not yet been quantified, and the relationship between the expression of this behavioral trait with that of the morphological traits has not yet been examined. Here, we experimentally showed that in midsummer soldiers behave more aggressively in response to artificial stimuli mimicking contact with a predator than they do in early summer. Furthermore, this variation correlated with the phenological variation of defensive morphology in soldier aphids. These results suggest that C. japonica defend their colony with not only strengthening soldier's morphological weapon but also strengthening soldier's aggressiveness when predator risk is high.
• Contacts with large, active individuals intensify the predation risk of small conspecifics

  Aya Yamaguchi, Kunio Takatsu, Osamu Kishida

  ECOLOGY 97 11 3206 - 3218 2016年11月 [査読有り][通常論文]
   

  Size variation within a population can influence the structure of ecosystem interactions, because ecological performance differs between individuals of different sizes. Although the impact of size variation in a predator species on the structure of interactions is well understood, our knowledge about how size variation in a prey species might modify the interactions between predators and prey is very limited. Here, by examining the interactions between predatory Hynobius retardatus salamander larvae and their prey, Rana pirica frog tadpoles, we investigated how large prey individuals affect the predation mortality of small prey conspecifics. First, in an experiment conducted in a field pond in which we manipulated the presence of salamanders and large tadpoles (i.e., large enough to protect them against salamander predation) with small tadpoles, we showed that in the presence of large tadpoles the mortality of small tadpoles from salamander predation was increased. On the basis of our observations of the activity of individuals, we hypothesized that active large tadpoles caused physical disturbances, which in turn caused the small tadpoles to move, and thus increased their encounter frequency with the predatory salamanders. To test this hypothesis, we conducted a laboratory experiment in small tanks with three players (i.e., one salamander as predator, one small tadpole as focal prey, and either a small or a large tadpole as the prospective movement inducer). In each tank, we manipulated the presence or absence of a movement inducer, and, when present, its size (large or small) and access (caged or uncaged) to the focal prey. In the presence of a large, uncaged movement inducer, the focal prey was more active and suffered from higher predation mortality compared with the other treatments, because the large movement inducer (unlike a small movement inducer) moved actively and, when uncaged, could stimulate movement of the focal prey through direct contact. The results indicated that high activity of large prey individuals and the resulting behavioral interactions with small conspecifics via direct contact indirectly increased the mortality of the small prey.
• Networks Depicting the Fine-Scale Co-Occurrences of Fungi in Soil Horizons

  Hirokazu Toju, Osamu Kishida, Noboru Katayama, Kentaro Takagi

  PLOS ONE 11 11 2016年11月 [査読有り][通常論文]
   

  Fungi in soil play pivotal roles in nutrient cycling, pest controls, and plant community succession in terrestrial ecosystems. Despite the ecosystem functions provided by soil fungi, our knowledge of the assembly processes of belowground fungi has been limited. In particular, we still have limited knowledge of how diverse functional groups of fungi interact with each other in facilitative and competitive ways in soil. Based on the high-throughput sequencing data of fungi in a cool-temperate forest in northern Japan, we analyzed how taxonomically and functionally diverse fungi showed correlated fine-scale distributions in soil. By uncovering pairs of fungi that frequently co-occurred in the same soil samples, networks depicting fine-scale co-occurrences of fungi were inferred at the O (organic matter) and A (surface soil) horizons. The results then led to the working hypothesis that mycorrhizal, endophytic, saprotrophic, and pathogenic fungi could form compartmentalized (modular) networks of facilitative, antagonistic, and/or competitive interactions in belowground ecosystems. Overall, this study provides a research basis for further understanding how interspecific interactions, along with sharing of niches among fungi, drive the dynamics of poorly explored biospheres in soil.
• An aquatic vertebrate can use amino acids from environmental water

  Noboru Katayama, Kobayashi Makoto, Osamu Kishida

  PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES 283 1839 20160996  2016年09月 [査読有り][通常論文]
   

  Conventional food-web theory assumes that nutrients from dissolved organic matter are transferred to aquatic vertebrates via long nutrient pathways involving multiple eukaryotic species as intermediary nutrient transporters. Here, using larvae of the salamander Hynobius retardatus as a model system, we provide experimental evidence of a shortcut nutrient pathway by showing that H. retardatus larvae can use dissolved amino acids for their growth without eukaryotic mediation. First, to explore which amino acids can promote larval growth, we kept individual salamander larvae in one of eight different high-concentration amino acid solutions, or in control water from which all other eukaryotic organisms had been removed. We thus identified five amino acids (lysine, threonine, serine, phenylalanine, and tyrosine) as having the potential to promote larval growth. Next, using N-15-labelled amino acid solutions, we demonstrated that nitrogen from dissolved amino acids was found in larval tissues. These results suggest that salamander larvae can take up dissolved amino acids from environmental water to use as an energy source or a growth-promoting factor. Thus, aquatic vertebrates as well as aquatic invertebrates may be able to use dissolved organic matter as a nutrient source.
• Overwintering larvae of Hynobius retardatus salamanders can consume invertebrate prey at very low temperatures

  Aya Yamaguchi, Osamu Kishida

  SALAMANDRA 52 1 45 - 47 2016年04月 [査読有り][通常論文]
  
• Antagonistic indirect interactions between large and small conspecific prey via a heterospecific predator

  Aya Yamaguchi, Osamu Kishida

  OIKOS 125 2 271 - 277 2016年02月 [査読有り][通常論文]
   

  Intrapopulation size variation strongly influences ecological interactions because individuals belonging to different size groups have distinct functions. Most demonstrations of the impacts of size variation in trophic systems have focused on size variation in predator species, and the consequences of size variation in prey species are less well understood. We investigated how prey size structure shapes intra- and interspecific interactions in experiments with a gape-limited predator (larvae of the salamander Hynobius retardatus) and its heterospecific prey (frog tadpoles, Rana pirica). We found that large and small tadpole size groups each increased mortality in the other group by intensifying salamander predation; this type of indirect interactions is called apparent competition. The antagonistic impacts on the prey size groups were caused by different size-specific mechanisms. By consuming small tadpoles, the salamanders grew large enough to consume large tadpoles. The activity of large tadpoles, by increasing the activity of the small tadpoles, may increase the number of encounters with the predator and thus small tadpole mortality. These results suggest that the magnitude of a predator's ecological role, such as whether a top-down trophic cascade is initiated, depends on size variation in its heterospecific prey.
• Response of a Wild Edible Plant to Human Disturbance: Harvesting Can Enhance the Subsequent Yield of Bamboo Shoots

  Noboru Katayama, Osamu Kishida, Rei Sakai, Shintaro Hayakashi, Chikako Miyoshi, Kinya Ito, Aiko Naniwa, Aya Yamaguchi, Katsunori Wada, Shiro Kowata, Yoshinobu Koike, Katsuhiro Tsubakimoto, Kenichi Ohiwa, Hirokazu Sato, Toru Miyazaki, Shinichi Oiwa, Tsubasa Oka, Shinya Kikuchi, Chikako Igarashi, Shiho Chiba, Yoko Akiyama, Hiroyuki Takahashi, Kentaro Takagi

  PLOS ONE 10 12 e0146228 - e0146228 2015年12月31日 [査読有り]
   

  Wild edible plants, ecological foodstuffs obtained from forest ecosystems, grow in natural fields, and their productivity depends on their response to harvesting by humans. Addressing exactly how wild edible plants respond to harvesting is critical because this knowledge will provide insights into how to obtain effective and sustainable ecosystem services from these plants. We focused on bamboo shoots of Sasa kurilensis, a popular wild edible plant in Japan. We examined the effects of harvesting on bamboo shoot productivity by conducting an experimental manipulation of bamboo shoot harvesting. Twenty experimental plots were prepared in the Teshio Experimental Forest of Hokkaido University and were assigned into two groups: a harvest treatment, in which newly emerged edible bamboo shoots were harvested (n = 10); and a control treatment, in which bamboo shoots were maintained without harvesting (n = 10). In the first year of harvesting (2013), bamboo shoot productivities were examined twice; i.e., the productivity one day after harvesting and the subsequent post-harvest productivity (2-46 days after harvesting), and we observed no difference in productivity between treatments. This means that there was no difference in original bamboo shoot productivity between treatments, and that harvesting did not influence productivity in the initial year. In contrast, in the following year (2014), the number of bamboo shoots in the harvested plots was 2.4-fold greater than in the control plots. These results indicate that over-compensatory growth occurred in the harvested plots in the year following harvesting. Whereas previous research has emphasized the negative impact of harvesting, this study provides the first experimental evidence that harvesting can enhance the productivity of a wild edible plant. This suggests that exploiting compensatory growth, which really amounts to less of a decline in productivity, may be s a key for the effective use of wild edible plants.
• Nonadditive impacts of temperature and basal resource availability on predator-prey interactions and phenotypes

  Zacharia J. Costa, Osamu Kishida

  OECOLOGIA 178 4 1215 - 1225 2015年08月 [査読有り][通常論文]
   

  Predicting the impacts of climate change on communities requires understanding how temperature affects predator-prey interactions under different biotic conditions. In cases of size-specific predation, environmental influences on the growth rate of one or both species can determine predation rates. For example, warming increases top-down control of food webs, although this depends on resource availability for prey, as increased resources may allow prey to reach a size refuge. Moreover, because the magnitude of inducible defenses depends on predation rates and resource availability for prey, temperature and resource levels also affect phenotypic plasticity. To examine these issues, we manipulated the presence/absence of predatory Hynobius retardatus salamander larvae and herbivorous Rana pirica tadpoles at two temperatures and three basal resource levels. and measured their morphology, behavior, growth and survival. Prior work has shown that both species express antagonistic plasticity against one another in which salamanders enlarge their gape width and tadpoles increase their body width to reach a size-refuge. We found that increased temperatures increased predation rates, although this was counteracted by high basal resource availability, which further decreased salamander growth. Surprisingly, salamanders caused tadpoles to grow larger and express more extreme defensive phenotypes as resource levels decreased under warming, most likely due to their increased risk of predation. Thus, temperature and resources influenced defensive phenotype expression and its impacts on predator and prey growth by affecting their interaction strength. Our results indicate that basal resource levels can modify the impacts of increased temperatures on predator-prey interactions and its consequences for food webs.
• Predator cannibalism can intensify negative impacts on heterospecific prey

  Kunio Takatsu, Osamu Kishida

  ECOLOGY 96 7 1887 - 1898 2015年07月 [査読有り][通常論文]
   

  Although natural populations consist of individuals with different traits, and the degree of phenotypic variation varies among populations, the impact of phenotypic variation on ecological interactions has received little attention, because traditional approaches to community ecology assume homogeneity of individuals within a population. Stage structure, which is a common way of generating size and developmental variation within predator populations, can drive cannibalistic interactions, which can affect the strength of predatory effects on the predator's heterospecific prey. Studies have shown that predator cannibalism weakens predatory effects on heterospecific prey by reducing the size of the predator population and by inducing less feeding activity of noncannibal predators. We predict, however, that predator cannibalism, by promoting rapid growth of the cannibals, can also intensify predation pressure on heterospecific prey, because large predators have large resource requirements and may utilize a wider variety of prey species. To test this hypothesis, we conducted an experiment in which we created carnivorous salamander (Hynobius retardatus) populations with different stage structures by manipulating the salamander's hatch timing (i.e., populations with large or small variation in the timing of hatching), and explored the resultant impacts on the abundance, behavior, morphology, and life history of the salamander's large heterospecific prey, Rana pirica frog tadpoles. Cannibalism was rare in salamander populations having small hatch-timing variation, but was frequent in those having large hatch-timing variation. Thus, giant salamander cannibals occurred only in the latter. We clearly showed that salamander giants exerted strong predation pressure on frog tadpoles, which induced large behavioral and morphological defenses in the tadpoles and caused them to metamorphose late at large size. Hence, predator cannibalism arising from large variation in the timing of hatching can strengthen predatory effects on heterospecific prey and can have impacts on various traits of both predator and prey. Because animals commonly broaden their diet as they grow, such negative impacts of predator cannibalism on the heterospecific prey may be common in interactions between predators and prey species of similar size.
• Transcriptome analysis of predator- and prey-induced phenotypic plasticity in the Hokkaido salamander (Hynobius retardatus)

  Masatoshi Matsunami, Jun Kitano, Osamu Kishida, Hirofumi Michimae, Toru Miura, Kinya Nishimura

  MOLECULAR ECOLOGY 24 12 3064 - 3076 2015年06月 [査読有り][通常論文]
   

  Predator- and prey-induced phenotypic plasticity is widely observed among amphibian species. Although ecological factors inducing diverse phenotypic responses have been extensively characterized, we know little about the molecular bases of variation in phenotypic plasticity. Larvae of the Hokkaido salamander, Hynobius retardatus, exhibit two distinct morphs: the presence of their prey, Rana pirica tadpoles, induces a broad-headed attack morph, and the presence of predatory dragonfly nymphs (Aeshna nigroflava) induces a defence morph with enlarged external gills and a high tail. To compare the genes involved in predator- and prey-induced phenotypic plasticity, we carried out a de novo transcriptome analysis of Hokkaido salamander larvae exposed to either prey or predator individuals. First, we found that the number of genes involved in the expression of the defence morph was approximately five times the number involved in the expression of the attack morph. This result is consistent with the fact that the predator-induced plasticity involves more drastic morphological changes than the prey-induced plasticity. Second, we found that particular sets of genes were upregulated during the induction of both the attack and defence morphs, but others were specific to the expression of one or the other morph. Because both shared and unique molecular mechanisms were used in the expression of each morph, the evolution of a new plastic phenotype might involve both the co-option of pre-existing molecular mechanisms and the acquisition of novel regulatory mechanisms.
• Gene expression profiles in Rana pirica tadpoles following exposure to a predation threat

  Tsukasa Mori, Yukio Yanagisawa, Yoichiro Kitani, Manabu Sugiyama, Osamu Kishida, Kinya Nishimura

  BMC GENOMICS 16 258  2015年04月 [査読有り][通常論文]
   

  Background: Rana pirica tadpoles show morphological changes in response to a predation threat: larvae of the dragonfly Aeshna nigroflava induce heightened tail depth, whereas larval salamander Hynobius retardatus induce a bulgy morphology with heightened tail depth. Although both predators induce similar tail morphologies, it is possible that there are functional differences between these tail morphs. Results: Here, we performed a discriminant microarray analysis using Xenopus laevis genome arrays to compare tail tissues of control and predator-exposed tadpoles. We identified 9 genes showing large-scale changes in their expression profile: ELAV-like1, methyltransferase like 7A, dolichyl-phosphate mannosyltransferase, laminin subunit beta-1, gremlin 1, BCL6 corepressor-like 1, and three genes of unknown identity. A further 80 genes showed greater than 5 fold differences in expression after exposure to dragonfly larvae and 81 genes showed altered expression after exposure to larval salamanders. Predation-threat responsive genes were identified by selecting genes that reverted to control levels of expression following removal of the predator. Thirteen genes were induced specifically by dragonfly larvae, nine others were salamander-specific, and sixteen were induced by both. Functional analyses indicated that some of the genes induced by dragonfly larvae caused an increase in laminins necessary for cell adhesion in the extracellular matrix. The higher expression of gremlin 1 and HIF1a genes after exposure to dragonfly larvae indicated an in vivo hypoxic reaction, while down-regulation of syndecan-2 may indicate impairment of angiogenesis. Exposure to larval salamanders caused down-regulation of XCIRP-1, which is known to inhibit expression of adhesion molecules; the tadpoles showed reduced expression of ca(E)-catenin, small muscle protein, dystrophin, and myosin light chain genes. Conclusion: The connective tissue of tadpoles exposed to larval salamanders may be looser. The differences in gene expression profiles induced by the two predators suggest that there are functional differences between the altered tail tissues of the two groups of tadpoles.
• Adaptive acceleration in growth and development of salamander hatchlings in cannibalistic situations

  Osamu Kishida, Ayumi Tezuka, Akiko Ikeda, Kunio Takatsu, Hirofumi Michimae

  Functional Ecology 29 4 469 - 478 2015年04月 [査読有り][通常論文]
   

  In most animal species, the hatchling stage is a highly vulnerable life-history stage. In many fish and amphibian species, hatchling abundance varies substantially among sites and years, with the result that selection strength in conspecific interactions such as cannibalism is also variable. The variability of selection leads species to evolve phenotypic plasticity, and adaptive trait changes in hatchlings that depend on the density of conspecifics can therefore be expected. However, plasticity strategies in response to cannibalistic interactions in this vulnerable life-history stage have received little attention. Because cannibalism success is dependent on the size balance between predator capturing organ and prey body, and also on the prey-capturing ability of the cannibal and the escape ability of its prey, we hypothesize that hatchlings will exhibit faster growth and development in response to conspecific interactions. We performed a series of experiments to test this hypothesis, using pre-feeding larvae of a cannibalistic salamander (Hynobius retardatus). Many traits of the hatchlings reared with conspecifics were larger than the same traits in those reared alone, because the former hatchlings grew faster and were more advanced developmentally. The time to the beginning of feeding was shorter, and swimming speed as an indicator of escape performance was faster, for hatchlings reared with conspecifics. Hatchlings reared with conspecifics more successfully cannibalized small hatchlings and were also highly resistant to being cannibalized by large conspecifics, compared with hatchlings reared alone. These differences in cannibalism success and avoidance of cannibalization were well explained by differences in gape and head size, respectively, between the interacting hatchlings. Therefore, acceleration of growth and development of hatchlings in the proximate presence of conspecifics may confer significant fitness advantages on hatchlings in a high-density cannibalistic situation. Developmental and growth plasticity may thus be a powerful adaptive mechanism that allows individuals to respond to the dynamic character of salamander populations in nature.
• Feedback between size balance and consumption strongly affects the consequences of hatching phenology in size-dependent predator-prey interactions

  Megumi Nosaka, Noboru Katayama, Osamu Kishida

  OIKOS 124 2 225 - 234 2015年02月 [査読有り][通常論文]
   

  In many size-dependent predator-prey systems, hatching phenology strongly affects predator-prey interaction outcomes. Early-hatched predators can easily consume prey when they first interact because they encounter smaller prey. However, this process by itself may be insufficient to explain all predator-prey interaction outcomes over the whole interaction period because the predator-prey size balance changes dynamically throughout their ontogeny. We hypothesized that hatching phenology influences predator-prey interactions via a feedback mechanism between the predator-prey size balance and prey consumption by predators. We experimentally tested this hypothesis in an amphibian predator-prey model system. Frog tadpoles Rana pirica were exposed to a predatory salamander larva Hynobius retardatus that had hatched 5, 12, 19 or 26 days after the frog tadpoles hatched. We investigated how the salamander hatch timing affected the dynamics of prey mortality, size changes of both predator and prey, and their subsequent life history (larval period and size at metamorphosis). The predator-prey size balance favoured earlier hatched salamanders, which just after hatching could successfully consume more frog tadpoles than later hatched salamanders. The early-hatched salamanders grew rapidly and their accelerated growth enabled them to maintain the predator-superior size balance; thus, they continued to exert strong predation pressure on the frog tadpoles in the subsequent period. Furthermore, frog tadpoles exposed to the early-hatched salamanders were larger at metamorphosis and had a longer larval period than other frog tadpoles. These results suggest that feedback between the predator-superior size balance and prey consumption is a critical mechanism that strongly affects the impacts of early hatching of predators in the short-term population dynamics and life history of the prey. Because consumption of large nutrient-rich prey items supports the growth of predators, a similar feedback mechanism may be common and have strong impacts on phenological shifts in size-dependent trophic relationships.
• Allometric equations for estimation of energy contents from body length for common amphibians (Hynobius retardatus and Rana pirica) in Hokkaido, Japan

  Kunio Takatsu, Osamu Kishida

  Herpetology Notes 8 187 - 191 2015年 [査読有り][通常論文]
  
• Dynamics of ecosystem carbon balance recovering from a clear-cutting in a cool-temperate forest

  Maricar Aguilos, Kentaro Takagi, Naishen Liang, Masahito Ueyama, Karibu Fukuzawa, Mutsumi Nomura, Osamu Kishida, Tatsuya Fukazawa, Hiroyuki Takahashi, Chikara Kotsuka, Rei Sakai, Kinya Ito, Yoko Watanabe, Yasumi Fujinuma, Yoshiyuki Takahashi, Takeshi Murayama, Nobuko Saigusa, Kaichiro Sasa

  Agricultural and Forest Meteorology 197 26 - 39 2014年10月 [査読有り]
  
• Herbivorous insect decreases plant nutrient uptake: the role of soil nutrient availability and association of below-ground symbionts

  Noboru Katayama, Alessandro O. Silva, Osamu Kishida, Masayuki Ushio, Satoshi Kita, Takayuki Ohgushi

  ECOLOGICAL ENTOMOLOGY 39 4 511 - 518 2014年08月 [査読有り][通常論文]
   

  1. Plants take nutrients from the rhizosphere via two pathways: (i) by absorbing soil nutrients directly via their roots and (n) indirectly via symbiotic associations with nutrient-providing microbes. Herbivorous insects can alter these pathways by herbivory, adding their excrement to the soil, and affecting plant microbe associations. 2. Little is known, however, about the effects of herbivorous insects on plant nutrient uptake. Greenhouse experiments with soybean, aphids, and rhizobia were carried out to examine the effects of aphids on plant nutrient uptake. 3. First, the inorganic soil nitrogen and the sugar in aphid honeydew between aphid-infected and -free plants were compared. It was found that aphid honeydew added 41 g M-2 of sugar to the soil, and that aphids decreased the inorganic soil nitrogen by 86%. This decrease may have been caused by microbial immobilisation of soil nitrogen followed by increased microbial abundance as a result of aphid honeydew, 4. Second, nitrogen forms in xylem sap between aphid-infected and -free plants were compared to examine nitrogen uptake. Aphids decreased the nitrogen uptake via both pathways, and strength of the impact on direct uptake via plant roots was greater than indirect uptake via rhizobia. The reduced nitrogen uptake by the direct pathway was as a result of microbial immobilisation, and that by the indirect pathway was probably because of the interaction of microbial immobilisation and carbon stress, which was caused by aphid infection, 5. The present results demonstrate that herbivorous insects can negatively influence the two pathways of plant nutrient uptake and alter their relative importance.
• Inducible offences affect predator-prey interactions and life-history plasticity in both predators and prey

  Osamu Kishida, Zacharia Costa, Ayumi Tezuka, Hirofumi Michimae

  JOURNAL OF ANIMAL ECOLOGY 83 4 899 - 906 2014年07月 [査読有り][通常論文]
   

  Phenotypic plasticity can have strong impacts on predator-prey interactions. Although much work has examined the effects of inducible defences, less understood is how inducible offences in predators affect predator-prey interactions and predator and prey phenotypes. Here, we examine the impacts of an inducible offence on the interactions and life histories of a cohort of predatory Hynobius retardatus salamander larvae and their prey, Rana pirica tadpoles. We examined larval (duration, survival) and post-metamorphic (size) traits of both species after manipulating the presence/absence of tadpoles and salamanders with offensive (broadened gape width) or non-offensive phenotypes in pond enclosures. Offensive phenotype salamanders reduced tadpole survival and metamorph emergence by 58% compared to tadpole-only treatments, and by over 30% compared to non-offensive phenotypes. Average time to metamorphosis of frogs was delayed by 30% in the presence of salamanders, although this was independent of salamander phenotype. Thus, offensive phenotype salamanders reduced the number of tadpoles remaining in the pond over time by reducing tadpole survival, not by altering patterns of metamorph emergence. Offensive phenotypes also caused tadpoles to metamorphose 19% larger than no salamander treatments and 6% larger than non-offensive phenotype treatments. Pooled across salamander treatments, tadpoles caused salamanders to reach metamorphosis faster and larger. Moreover, in the presence of tadpoles, offensive phenotype salamanders metamorphosed 25% faster and 5% larger than non-offensive phenotype salamanders, but in their absence, neither their size nor larval period differed from non-offensive phenotype individuals. To our knowledge, this study is the first to demonstrate that inducible offences in predators can have strong impacts on predator and prey phenotypes across multiple life stages. Since early metamorphosis at a larger size has potential fitness advantages, the impacts of offensive phenotypes on frog and salamander life histories likely have significant consequences for individuals and populations. Furthermore, increased predation on tadpoles likely causes offensive phenotype individuals to have strong impacts on pond communities. Future studies should examine the fitness consequences of morphological and life-history plasticity across multiple life stages and should address the population and community level consequences of offensive phenotypes.
• Environment-dependent trade-offs and phenotypic plasticity in metamorphic timing

  Hirofumi Michimae, Ayumi Tezuka, Takeshi Emura, Osamu Kishida

  EVOLUTIONARY ECOLOGY RESEARCH 16 7 617 - 629 2014年 [査読有り][通常論文]
   

  Background: Fitness trade-offs of plastic traits between alternative environments are a prerequisite for the evolution of phenotypic plasticity; however, the costs associated with plastic traits have yet to be determined. Most empirical studies have assessed the costs of plastic traits by investigating just two environments (to elicit plasticity), and only one or two environments to evaluate the consequences of plasticity. In contrast, in nature, organisms are constantly subjected to multiple environments, and the expression and magnitude of the costs of plastic traits are occasionally context-dependent. Objective: Analyse the costs of plastic traits across multiple environments. Methods: We determined the benefits and costs of two plastic responses (predator-and prey-induced morphologies) of larvae of the salamander Hynobius retardatus to larval survival, time to metamorphosis, and body size at metamorphosis in three different environments [using tadpoles of an anuran frog as prey, larvae of a predatory dragonfly, or no change agent (conspecific larvae only)]. Results: The benefits of the alternative phenotypes were evident in the two inducing environments, but the costs were greater or more easily detected in crossover environments. The trade-offs appeared in combinations in the crossover environments, and thus were context-dependent. Conclusions: The cross-environmental costs of plastic traits are necessary for the evolution of phenotypic plasticity. Our findings highlight the importance of measuring the costs and benefits of plastic traits across multiple environments.
• Aphids decelerate litter nitrogen mineralisation through changes in litter quality

  Noboru Katayama, Alessandro Oliveria Silva, Osamu Kishida, Takayuki Ohgushi

  ECOLOGICAL ENTOMOLOGY 38 6 627 - 630 2013年12月 [査読有り][通常論文]
   

  Herbivorous insects may have significant impacts on litter decomposition through modification of plant litter quality and quantity. The effects of herbivorous insects on decomposition processes are of growing interest. Here, experiments were conducted to examine how sap-feeding aphids modify plant litter and whether the aphid-induced modification influences litter decomposition processes, using a plant-herbivore system consisting of soybean [Glycine max (L.)] and soybean aphids (Aphis glycines Matsumura). First, litter traits produced by aphid-free and aphid-infected plants were compared, and it was found that aphids did not affect litter mass and carbon concentration, but significantly decreased the nitrogen concentration. Such aphid-mediated modification of litter quality may cause deceleration of litter decomposition as the higher C/N ratio inhibits litter decomposition. A decomposition experiment was then carried out to compare the decomposition of litter between the aphid-free and aphid-infected plants. No impacts of aphid herbivory were found on litter carbon mineralisation but negative impacts were found on nitrogen mineralisation. Litter nitrogen mineralisation of aphid-infected plants decreased by 40% and 28% compared with that of aphid-free plants 1 and 3months after commencement of the experiment, respectively. The experimental results clearly showed that aphids decelerated litter nitrogen mineralisation by modifying litter quality.
• Soldiers with large weapons in predator-abundant midsummer: phenotypic plasticity in a eusocial aphid

  Mitsuru Hattori, Osamu Kishida, Takao Itino

  EVOLUTIONARY ECOLOGY 27 5 847 - 862 2013年09月 [査読有り][通常論文]
   

  Eusocial aphids produce sterile individuals ("soldiers") that specialize behaviorally and morphologically to protect their colony from predators, while production of soldiers can negatively affect colony growth because of reproductive allocation and opportunity cost. Hence, a cost-saving soldier production strategy is expected to be favored. Here, we hypothesize that, to save the cost, a eusocial aphid Ceratovacuna japonica produces soldiers with smaller weapon in the season when predators are not abundant. The abundance of two specialist lepidopteran predators (i.e., Taraka hamada and Atkinsonia ignipicta) of C. japonica dramatically increased, and aphid colony size significantly decreased, from July to August. In line with these, the soldiers in August had larger weapons (i.e., frontal horns) than those in June, indicating a correlational increase in weapon size with predation pressure. We predict that a reliable prospective signal indicating the coming of midsummer (environmental temperature) induces mother aphids to produce soldiers with larger weapons. Experiments clarified that soldiers produced at 20 A degrees C (typical temperature of July to August) had larger weapons than those produced at 15 A degrees C (typical temperature of May to July). Such phenotypic plasticity appears to be adaptive to maximize the fitness of C. japonica under a temporally variable but predictable predation environment. These results indicate that C. japonica aphids not merely have distinctive reproductive-and soldier castes, but also produce differentially armed soldiers in a habitat with temporally changing predation risks.
• Overwintered Hynobius retardatus salamander larvae can induce defensive bulgy morph in Rana pirica tadpoles

  Kishida O, Tezuka A

  Herpetology Notes 6 183 - 185 2013年03月 [査読有り][通常論文]
  
• An offensive predator phenotype selects for an amplified defensive phenotype in its prey

  Kunio Takatsu, Osamu Kishida

  Evolutionary Ecology 27 1 1 - 11 2013年01月 [査読有り][通常論文]
   

  Inducible defenses of prey and inducible offenses of predators are examples of adaptive phenotypic plasticity. Although evolutionary ecologists have paid considerable attention to the adaptive significances of these strategies, they have rarely focused on their evolutionary impacts on the interacting species. Because the functional phenotypes of predator and prey determine strength of interactions between the species, the inducible plasticity can modify selective pressure on trait distribution and, ultimately, trait evolution in the interacting species. We experimentally tested this hypothesis in a predator-prey system composed of salamander larvae (Hynobius retardatus) and frog tadpoles (Rana pirica) capable of expressing antagonistic inducible offensive or defensive traits, an enlarged gape in the salamander larvae and a bulgy body in the tadpoles, when predator-prey interactions are strong. We examined selection strength on the tadpole's defensive trait by comparing survival rates of tadpoles with different defensive levels under predation pressure from offensive or non-offensive salamander larvae. Survival rates of more-defensive tadpoles were greater than those of less-defensive tadpoles only when the tadpoles were exposed to offensive salamander larvae; thus, the predator's offensive phenotype could select for an amplified defensive phenotype in their prey. As the expression of inducible offenses by H. retardatus larvae depends greatly on the composition of its ecological community, the inducible defensive bulgy morph of R. pirica tadpoles might have evolved in response to the variable expression of the H. retardatus offensive larval phenotype.
• Buying time for colony mates: The anti-predatory function of soldiers in the eusocial aphid Ceratovacuna japonica (Homoptera, Hormaphidinae)

  M. Hattori, O. Kishida, T. Itino

  Insectes Sociaux 60 15 - 21 2013年01月 [査読有り][通常論文]
   

  Eusocial aphids produce sterile individuals (soldiers) that specialize in colony protection. Killing predators is often considered the main function of soldiers. In this study, we tested the effect of harassment by soldiers of a eusocial aphid, Ceratovacuna japonica (Homoptera, Hormaphidinae), on predation by this species' natural enemy, the larvae of Atkinsonia ignipicta (Lepidoptera, Stathmopodidae). We experimentally introduced some aphids and a predator to petri dishes and compared the survivorship of first-instar reproductives in the presence and absence of soldiers. We showed that soldiers can reduce the rate of predation on their colony mates without killing the predators. When predators encountered soldiers, they did not attempt to prey on them. Instead, they evaded them and often started to make a nest by spinning silken threads. The soldiers, in contrast, waved their forelegs and attacked the predator, and they sometimes succeeded in grasping the predator's body. Because the predator used its mandibles to remove any soldier that succeeded in grasping its body, the soldier did not kill the predator. The reduction of predation was apparently caused by the delay of predation resulting from the harassment behavior of the soldiers. In eusocial aphids, a defensive strategy that delays predation may buy the soldiers' colony mates time to reproduce or to escape from the predator. © 2012 International Union for the Study of Social Insects (IUSSI).
• Histological and MS spectrometric analyses of the modified tissue of bulgy form tadpoles induced by salamander predation

  Tsukasa Mori, Yoichiro Kitani, Jun Ogihara, Manabu Sugiyama, Goshi Yamamoto, Osamu Kishida, Kinya Nishimura

  BIOLOGY OPEN 1 4 308 - 317 2012年04月 [査読有り][通常論文]
   

  The rapid induction of a defensive morphology by a prey species in face of a predation risk is an intriguing in ecological context; however, the physiological mechanisms that underlie this phenotypic plasticity remain uncertain. Here we investigated the phenotypic changes shown by Rana pirica tadpoles in response to a predation threat by larvae of the salamander Hynobius retardatus. One such response is the bulgy morph phenotype, a relatively rapid swelling in size by the tadpoles that begins within 4 days and reaches a maximum at 8 to 10 days. We found that although the total volume of bodily fluid increased significantly (P<0.01) in bulgy morph tadpoles, osmotic pressure was maintained at the same level as control tadpoles by a significant increase (P<0.01) in Na and Cl ion concentrations. In our previous report, we identified a novel frog gene named pirica that affects the waterproofing of the skin membrane in tadpoles. Our results support the hypothesis that predator-induced expression of pirica on the skin membrane causes retention of absorbed water. Midline sections of bulgy morph tadpoles showed the presence of swollen connective tissue beneath the skin that was sparsely composed of cells containing hyaluronic acid. Mass spectrographic (LC-MS/MS) analysis identified histone H3 and 14-3-3 zeta as the most abundant constituents in the liquid aspirated from the connective tissue of bulgy tadpoles. Immunohistochemistry using antibodies against these proteins showed the presence of non-chromatin associated histone H3 in the swollen connective tissue. Histones and 14-3-3 proteins are also involved in antimicrobial activity and secretion of antibacterial proteins, respectively. Bulgy tadpoles have a larger surface area than controls, and their skin often has bite wounds inflicted by the larval salamanders. Thus, formation of the bulgy morph may also require and be supported by activation of innate immune systems. (C) 2012. Published by The Company of Biologists Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial Share Alike License (http://creativecommons.org/licenses/by-nc-sa/3.0).
• Predation risk suppresses the positive feedback between size structure and cannibalism

  Osamu Kishida, Geoffrey C. Trussell, Ayaka Ohno, Shinya Kuwano, Takuya Ikawa, Kinya Nishimura

  JOURNAL OF ANIMAL ECOLOGY 80 6 1278 - 1287 2011年11月 [査読有り][通常論文]
   

  1. Cannibalism can play a prominent role in the structuring and dynamics of ecological communities. Previous studies have emphasized the importance of size structure and density of cannibalistic species in shaping short- and long-term cannibalism dynamics, but our understanding of how predators influence cannibalism dynamics is limited. This is despite widespread evidence that many prey species exhibit behavioural and morphological adaptations in response to predation risk. 2. This study examined how the presence and absence of predation risk from larval dragonflies Aeshna nigroflava affected cannibalism dynamics in its prey larval salamanders Hynobius retardatus. 3. We found that feedback dynamics between size structure and cannibalism depended on whether dragonfly predation risk was present. In the absence of dragonfly risk cues, a positive feedback between salamander size structure and cannibalism through time occurred because most of the replicates in this treatment contained at least one salamander larvae having an enlarged gape (i.e. cannibal). In contrast, this feedback and the emergence of cannibalism were rarely observed in the presence of the dragonfly risk cues. Once salamander size divergence occurred, experimental reversals of the presence or absence of dragonfly risk cues did not alter existing cannibalism dynamics as the experiment progressed. Thus, the effects of risk on the mechanisms driving cannibalism dynamics likely operated during the early developmental period of the salamander larvae. 4. The effects of dragonfly predation risk on behavioural aspects of cannibalistic interactions among hatchlings may prohibit the initiation of dynamics between size structure and cannibalism. Our predation trials clearly showed that encounter rates among hatchlings and biting and ingestion rates of prospective prey by prospective cannibals were significantly lower in the presence vs. absence of dragonfly predation risk even though the size asymmetry between cannibals and victims was similar in both risk treatments. These results suggest that dragonfly risk cues first suppress cannibalism among hatchlings and then prevent size variation from increasing through time. 5. We suggest that the positive feedback dynamics between size structure and cannibalism and their modification by predation risk may also operate in other systems to shape the population dynamics of cannibalistic prey species as well as overall community dynamics.
• Coevolution of phenotypic plasticity in predator and prey: why are inducible offenses rarer than inducible defenses?

  Akihiko Mougi, Osamu Kishida, Yoh Iwasa

  EVOLUTION 65 4 1079 - 1087 2011年04月 [査読有り][通常論文]
   

  Inducible defenses of prey and inducible offenses of predators are drastic phenotypic changes activated by the interaction between a prey and predator. Inducible defenses occur in many taxa and occur more frequently than inducible offenses. Recent empirical studies have reported reciprocal phenotypic changes in both predator and prey. Here, we model the coevolution of inducible plasticity in both prey and predator, and examine how the evolutionary dynamics of inducible plasticity affect the population dynamics of a predator-prey system. Under a broad range of parameter values, the proportion of predators with an offensive phenotype is smaller than the proportion of prey with a defensive phenotype, and the offense level is relatively lower than the defense level at evolutionary end points. Our model also predicts that inducible plasticity evolves in both species when predation success depends sensitively on the difference in the inducible trait value between the two species. Reciprocal phenotypic plasticity may be widespread in nature but may have been overlooked by field studies because offensive phenotypes are rare and inconspicuous.
• Trait-mediated indirect interactions in ecological communities SPECIAL FEATURE: PREFACE

  Shunsuke Utsumi, Osamu Kishida, Takayuki Ohgushi

  POPULATION ECOLOGY 52 4 457 - 459 2010年10月 [査読有り][通常論文]
  
• Evolutionary ecology of inducible morphological plasticity in predator-prey interaction: toward the practical links with population ecology

  Osamu Kishida, Geoffrey C. Trussell, Akihiko Mougi, Kinya Nishimura

  POPULATION ECOLOGY 52 1 37 - 46 2010年01月 [査読有り][通常論文]
   

  The outcome of species interactions is often strongly influenced by variation in the functional traits of the individuals participating. A rather large body of work demonstrates that inducible morphological plasticity in predators and prey can both influence and be influenced by species interaction strength, with important consequences for individual fitness. Much of the past research in this area has focused on the ecological and evolutionary significance of trait plasticity by studying single predator-prey pairs and testing the performance of individuals having induced and noninduced phenotypes. This research has thus been critical in improving our understanding of the adaptive value of trait plasticity and its widespread occurrence across species and community types. More recently, researchers have expanded this foundation by examining how the complexity of organismal design and community-level properties can shape plasticity in functional traits. In addition, researchers have begun to merge evolutionary and ecological perspectives by linking trait plasticity to community dynamics, with particular attention on trait-mediated indirect interactions. Here, we review recent studies on inducible morphological plasticity in predators and their prey with an emphasis on internal and external constraints and how the nature of predator-prey interactions influences the expression of inducible phenotypes. In particular, we focus on multiple-trait plasticity, flexibility and modification of inducible plasticity, and reciprocal plasticity between predator and prey. Based on our arguments on these issues, we propose future research directions that should better integrate evolutionary and population studies and thus improve our understanding of the role of phenotypic plasticity in predator-prey population and community dynamics.
• Inducible defenses in prey intensify predator cannibalism

  Osamu Kishida, Geoffrey C. Trussell, Kinya Nishimura, Takayuki Ohgushi

  ECOLOGY 90 11 3150 - 3158 2009年11月 [査読有り][通常論文]
   

  Trophic cascades are often a potent force in ecological communities, but abiotic and biotic heterogeneity can diffuse their influence. For example, inducible defenses in many species create variation in prey edibility, and size-structured interactions, such as cannibalism, can shift predator diets away from heterospecific prey. Although both factors diffuse cascade strength by adding heterogeneity to trophic interactions, the consequences of their interaction remain poorly understood. We show that inducible defenses in tadpole prey greatly intensify cannibalism in predatory larval salamanders. The likelihood of cannibalism was also strongly influenced by asymmetries in salamander size that appear to be most important in the presence of defended prey. Hence, variation in prey edibility and the size structure of the predator may synergistically affect predator-prey population dynamics by reducing prey mortality and increasing predator mortality via cannibalism. We also suggest that the indirect effects of prey defenses may shape the evolution of predator traits that determine diet breadth and how trophic dynamics unfold in natural systems.
• Reciprocal phenotypic plasticity can lead to stable predator-prey interaction

  Akihiko Mougi, Osamu Kishida

  JOURNAL OF ANIMAL ECOLOGY 78 6 1172 - 1181 2009年11月 [査読有り][通常論文]
   

  P>1. Inducible defences of prey and inducible offences of predators are prevalent strategies in trophic interactions with temporal variation. Due to the inducible properties of the functional traits themselves, which drive the dynamic predator-prey relationship on an ecological time-scale, predator and prey may reciprocally interact through their inducible traits (i.e. reciprocal phenotypic plasticity). 2. Although overwhelming evidence of the stabilizing effect of inducible traits in either species on community dynamics forcefully suggests a critical ecological role for reciprocal plasticity in predator-prey population dynamics, our understanding of its ecological consequences is very limited. 3. Within a mathematical modelling framework, we investigated how reciprocal plasticity influences the stability of predator-prey systems. 4. By assuming two types of phenotypic shift, a density-dependent shift and an adaptive phenotypic shift, we examined two interaction scenarios with reciprocal plasticity: (i) an arms-race-like relationship, in which the defensive prey phenotype is more protective against both predator phenotypes (i.e. normal and offensive) than the normal prey phenotype, and the offensive predator is a more efficient consumer, preying upon both prey phenotypes (i.e. normal and defensive), than the normal predator and (ii) a matching response-like relationship, in which the offensive predator consumes more defensive prey and fewer normal prey than the normal predator. 5. Results of both phenotypic shift models consistently suggest that given the used set of parameter values, the arms-race-like reciprocal plasticity scenario has the largest stability area, when compared with the other scenarios. In particular, higher stability is achieved when the prey exhibits a high-performance inducible defence. Furthermore, this stabilization is so strong that the destabilizing effects of enrichment may be eliminated, even though the higher flexibility of plasticity does not always stabilize a system. 6. Recent empirical studies support our model predictions. Clear-cut examples of reciprocal phenotypic plasticity show an arms-race-like relationship in which prey species exhibit induced high-performance defences. We may need to re-examine reported predator-prey interactions in which predator or prey exhibits inducible plasticity to determine whether arms-race-like reciprocal plasticity is a general ecological phenomenon.
• Identification of a novel Uromodulin-like gene related to predator-induced bulgy morph in anuran tadpoles by functional microarray analysis

  Tsukasa Mori, Hiroko Kawachi, Chiharu Imai, Manabu Sugiyama, Youichi Kurata, Osamu Kishida, Kinya Nishimura

  PLOS ONE 4 6 e5936  2009年06月 [査読有り][通常論文]
   

  Tadpoles of the anuran species Rana pirica can undergo predator-specific morphological responses. Exposure to a predation threat by larvae of the salamander Hynobius retardatus results in formation of a bulgy body (bulgy morph) with a higher tail. The tadpoles revert to a normal phenotype upon removal of the larval salamander threat. Although predator-induced phenotypic plasticity is of major interest to evolutionary ecologists, the molecular and physiological mechanisms that control this response have yet to be elucidated. In a previous study, we identified various genes that are expressed in the skin of the bulgy morph. However, it proved difficult to determine which of these were key genes in the control of gene expression associated with the bulgy phenotype. Here, we show that a novel gene plays an important role in the phenotypic plasticity producing the bulgy morph. A functional microarray analysis using facial tissue samples of control and bulgy morph tadpoles identified candidate functional genes for predator-specific morphological responses. A larger functional microarray was prepared than in the previous study and used to analyze mRNAs extracted from facial and brain tissues of tadpoles from induction-reversion experiments. We found that a novel uromodulin-like gene, which we name here pirica, was up-regulated and that keratin genes were down-regulated as the period of exposure to larval salamanders increased. Pirica consists of a 1296 bp open reading frame, which is putatively translated into a protein of 432 amino acids. The protein contains a zona pellucida domain similar to that of proteins that function to control water permeability. We found that the gene was expressed in the superficial epidermis of the tadpole skin.
• Top-down effects on antagonistic inducible defense and offense

  Osamu Kishida, Geoffrey C. Trussell, Kinya Nishimura

  ECOLOGY 90 5 1217 - 1226 2009年05月 [査読有り][通常論文]
   

  Antagonistic phenotypic plasticity may strongly influence trait evolution in tightly interacting predator-prey pairs as well as the role that trait plasticity plays in community dynamics. Most work on trait plasticity has focused on single predator-prey pairs, but prey must often contend with multiple predators in natural environments. Hence, a better understanding of the evolutionary and ecological significance of phenotypic plasticity requires experiments that examine how multiple predators shape prey trait plasticity. Here, using a simple food chain consisting of a top predator (dragonfly larvae, Aeshna nigroflava), an intermediate predator (salamander larvae, Hynobius retardatus), and frog (Rana pirica) tadpoles as prey, we show that the presence of dragonfly risk cues substantially modifies the intensity of antagonistic morphological plasticity in both amphibians. In the absence of dragonflies, tadpoles produced bulgier bodies in response to salamanders, and salamanders responded to this defense by enlarging their gape size. However, in the presence of dragonfly risk cues, the expression of both antagonistic traits was significantly reduced because tadpoles and salamanders produced phenotypes that are more effective against dragonfly predators. Thus, the reduced antagonism likely emerged, in part, because the benefits of antagonistic trait expression were outweighed by the potential cost of increased vulnerability to dragonfly predation. In addition, our results suggest that when all three species were present, salamander activity levels, which influence the amount of signals required to induce antagonistic traits, were more strongly affected by dragonfly risk cues than were tadpole activity levels. This species-specific difference in activity levels was likely responsible for the reduced tadpole mortality caused by salamanders in the presence vs. absence of dragonfly risk cues. Hence, dragonflies had a positive trait-mediated indirect effect on tadpoles by modifying both the morphological and behavioral traits of salamanders.
• Direct and indirect induction of a compensatory phenotype that alleviates the costs of an Inducible defense

  Tadashi Iwami, Osamu Kishida, Kinya Nishimura

  PLOS ONE 2 10 e1084  2007年10月 [査読有り][通常論文]
   

  Organisms often exhibit phenotypic plasticity in multiple traits in response to impending environmental change. Multiple traits phenotypic plasticity is complex syndrome brought on by causal relations in ecological and physiological context. Larvae of the salamander Hynobius retardatus exhibit inducible phenotypic plasticity of two traits, when at risk of predation by dragonfly larvae. One induced phenotype is an adaptive defense behaviour, i.e., stasis at the bottom of water column, directly triggered by the predation risk. Another one is a compensatory phenotype, i.e., enlarged external gills, for an unavoidable cost (hypoxia) associated with the induced defense. We identified two ways by which this compensatory phenotype could be induced. The compensatory phenotype is induced in response to not only the associated hypoxic conditions resulting from the induced defense but also the most primary but indirect cause, presence of the predator.
• Geographic variation in a predator-induced defense and its genetic basis

  Osamu Kishida, Geoffrey C. Trussell, Kinya Nishimura

  ECOLOGY 88 8 1948 - 1954 2007年08月 [査読有り][通常論文]
   

  Predator-induced morphological defenses are a well-known form of phenotypic plasticity, but we continue to have a limited understanding of geographic variation in these responses and its genetic basis. Here we examine genetic variation and geographic differentiation in the inducible defenses of tadpoles (Rana pirica) in response to predatory salamander larvae (Hynobius retardatus). To do so, we crossed male and female frogs from a "mainland" Japanese island having predaceous salamanders and a more isolated island not having predaceous salamanders and raised resulting offspring in the presence and absence of H. retardatus. Mainland tadpoles exhibited a higher capacity to express the inducible morphology (a more bulgy body) than those from the predator-free island, and expression of the bulgy morph in mainland-island hybrids produced phenotypes that were intermediate to those produced by pure crosses. In addition, parental sex had no effect on expression of the bulgy morph. Our results support the hypothesis that geographic variation in inducible defenses is linked to the additive effects of autosomal alleles that are shaped by differences in historical exposure to the inducing predator.
• 臨機応変 : オタマジャクシの柔軟な防御形態変化(<特集1>表現型の可塑性 : その適応的意義の探求)

  岸田 治, 西村 欣也

  日本生態学会誌 57 1 40 - 47 日本生態学会 2007年03月31日 [査読有り][通常論文]
   

  多くの動物は、捕食者に出会うと逃げたり隠れたりするが、形さえも変化させ捕食を回避しようとするものもいる。形態の変化による防御戦略は誘導防御形態戦略とよばれ、多様な生物分類群でみられる表現型可塑性として知られる。最近の研究では、捕食者動物は、ただ捕食されにくい形に変わるだけでなく、その変化が柔軟であり、捕食者環境の時間的・空間的な変異によく対応していることが知られている。本稿では、エゾアカガエルのオタマジャクシの捕食者誘導形態の防御機能と、柔軟な形態変化能について紹介する。エゾアカガエルのオタマジャクシは、捕食者のエゾサンショウウオの幼生とオオルリボシヤンマのヤゴに対して、それぞれに特異的な形態を発現する。サンショウウオ幼生によって誘導された膨満型の形態はサンショウウオ幼生による丸のみを妨げ、ヤゴによって誘導された高尾型の形態はヤゴによる捕食を回避するために有効である。これらの形態変化は柔軟性に富んでおり、一度、どちらかの捕食者に対して特異的な防御形態を発現した後でも、捕食者が交替したときには、新たな捕食者に特異的な防御形態へ変化できる。また、捕食の危険が取り除かれたときは元の形態へと戻る。捕食者特異的な形態の互換性は、捕食者種に特異的な防御形態誘導を獲得するうえで重要な役割を果たしたと考えられる。また、形態変化の可逆性は防御にコストがかかることを示唆している。これらの形態変化...
• Reciprocal phenotypic plasticity in a predator-prey interaction between larval amphibians

  Osamu Kishida, Yuuki Mizuta, Kinya Nishimura

  ECOLOGY 87 6 1599 - 1604 2006年06月 [査読有り][通常論文]
   

  In biological interactions, phenotypic change in interacting organisms induced by their interaction partners causes a substantial shift in some environmental factor of the partners, which may subsequently change their phenotype in response to that modified environmental factor. Few examples of such arms-race-like plastic responses, known as reciprocal phenotypic plasticity, have been identified in predator - prey interactions. We experimentally identified a reciprocal defensive plastic response of a prey species against a predator with a predaceous phenotype using a model system of close predator - prey interaction. Rana pirica tadpoles ( the prey species) were reared with larvae of the salamander Hynobius retardatus ( the predator species) having either a predaceous or a typical, nonpredaceous phenotype. The H. retardatus larvae with the predaceous phenotype, which is known to be induced by the presence of R. pirica tadpoles, induced a more defensive phenotype in the tadpoles than did larvae with the typical phenotype. The result suggests that the reciprocal phenotypic plasticity of R. pirica tadpoles is in response to a phenotype-specific signal under a close-signal recognition process.
• Flexible architecture of inducible morphological plasticity

  O Kishida, K Nishimura

  Journal of Animal Ecology 75 3 705 - 712 2006年05月 [査読有り][通常論文]
   

  Predator-induced morphological defences are produced in response to an emergent predator regime. In natural systems, prey organisms usually experience temporal shifting of the composition of the predator assemblage and of the intensity of predation risk from each predator species. Although, a repetitive morphological change in response to a sequential shift of the predator regime such as alteration of the predator species or diminution of the predation risk may be adaptive, such flexible inducible morphological defences are not ubiquitous. We experimentally addressed whether a flexible inducible morphological defence is accomplished in response to serial changes in the predation regime, using a model prey species which adopt different defensive morphological phenotypes in response to different predator species. Rana pirica (Matsui) tadpoles increased body depth and tail depth against the predatory larval salamander Hynobius retardatus (Dunn); on the other hand, they only increased tail depth against the predatory larval dragonfly Aeshna nigroflava (Martin). Rana pirica tadpoles with the predator-specific phenotypes were subjected to removal or exchange of the predator species. After removal of the predator species, tadpoles with each predator-specific phenotype changed their phenotype to the nondefensive basic one, suggesting that both predator-specific phenotypes are costly to maintain. After an exchange of the predator species, tadpoles with each predator-specific phenotype reciprocally, flexibly shifted their phenotype to the now more suitable predator-specific one only by modifying their body part. The partial modification can effectively reduce time and energy expenditures involved in repetitive morphological changes, and therefore suggest that the costs of the flexible morphological changes are reduced.
• Genetic basis of phenotypic plasticity for predator-induced morphological defenses in anuran tadpole, Rana pirica, using cDNA subtraction and microarray analysis

  Tsukasa Mori, Ikuei Hiraka, Youichi Kurata, Hiroko Kawachi, Osamu Kishida, Kinya Nishimura

  Biochemical and Biophysical Research Communications 330 4 1138 - 1145 2005年05月 [査読有り]
  
• Multiple inducible defences against multiple predators in the anuran tadpole, Rana pirica

  Osamu Kishida, Kinya Nishimura

  Evolutionary Ecology Research 7 4 619 - 631 2005年05月 [査読有り][通常論文]
   

  Question: What conditions are required for evolution of predator-specific inducible defences? Hypotheses: (1) Prey organisms distinguish among predators to which they are exposed. (2). P Prey individuals with a predator-specific defence must attain higher survivorship than those with a mismatched defensive phenotype. Organisms: Prey, anuran tadpoles (Rana pirica); biting type predator, dragonfly larvae (Aeshna nigroflava); swallowing type predator, salamander larvae (Hynobius retardatus). Methods: Rana pirica tadpoles were exposed to the predator signal in close proximity to or remote from the dragonfly larvae or the salamander larvae to determine whether the tadpoles develop predator-specific morphologies and whether they utilize predator-specific signals in the induction process. We conducted predation trials to determine whether the tadpoles with induced phenotypes were more resistant to the attack in the corresponding predator environment. Results: Rana pirica tadpoles developed predator-specific morphologies in response to exposure to two different types of predator. The tadpoles discriminated between the predators that is, different signals were required to develop the specific phenotypes in the induction process. The survival rate of tadpoles of specific phenotypes was higher than that of tadpoles of mismatched or non-induced phenotypes when exposed to predation by the corresponding predators.
• Genetic basis of phenotypic plasticity for predator-induced morphological defenses in anuran tadpole, Rana pirica, using cDNA subtraction and microarray analysis

  T Mori, Hiraka, I, Y Kurata, H Kawachi, O Kishida, K Nishimura

  BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 330 4 1138 - 1145 2005年05月 [査読無し][通常論文]
   

  Anuran tadpoles (Rana pirica) are induced to develop a higher tail and a bulgy body as predator-specific morphological responses when they are exposed to predatory larval salamanders. Subtractive hybridization was performed using induced tadpole body skin and normal tadpoles' body skin. A total of 196 clones showed higher expression, and 104 clones showed lower expression, when they formed bulgy bodies. In the subtraction, carboxypeptidase 13, trypsinogen, elastase 1, fibrinogen, elastase 11, triacyl-glycerol lipase, and alpha 1-antitrypsin genes showed lower expression. In contrast, RT-like protein, bullous pemphigoid antigen, phosphoserine aminotransferase, uromodulin, tetranectin, chaperonin-like protein, zinc finger protein, osteonectin, aldehyde dehydrogenase, Sec 23A protein, and ribosomal protein showed higher gene expression. Microarray analysis was also performed using this subtracted cDNA (nine replicates). Results of the microarray data essentially corresponded with those of the subtraction data, and the degree of the suppressed genes was much stronger than that of the expressed genes. Carboxypeptidase B showed the strongest suppression, and its inhibition range was from 1/100 to 3/100 compared with that of control body skin. Strong suppression was also observed with trypsinogen, elastase 1, fibrinogen, and elastase 11 as well. These results can be interpreted as increases of fibrinolysis by strong depression of both carboxypeptidase B and other genes simultaneously, resulting in the retention of blood vessels and facilitating the circulation of blood. Expression was observed in phosphoserine aminotransferase, aldehyde dehydrogenase, RT-related protein, chaperonin-like protein, tetranectin, bullous pemphigoid antigen, uromodulin, and Sec 23A protein. They were significantly (p < 0.05) increased and were at least 1.5 times greater compared with the control. From the appearance, it seems that the bulgy shaped body is highly connecting to the bullous pemphigoid (BP) antigen that causes the skin blistering disorder, and tetranectin and uromodulin may be related to the extracell matrix through myogenesis, protein secretion, and ion transport, respectively. Since the RT-related protein gene derived from retrotransposon (L1) is known to disrupt mammalian transcriptomes, retrotransposon may be involved with phenotypic plasticity for morphological defense by Rana prica against predator threat. (c) 2005 Elsevier Inc. All rights reserved.
• Bulgy tadpoles: inducible defense morph

  O Kishida, K Nishimura

  OECOLOGIA 140 3 414 - 421 2004年08月 [査読有り][通常論文]
   

  Predator induced morphological defenses are marked morphological shifts induced directly by cues associated with a predator. Generally, remote cues, i.e., chemical substances emitted from predators or injured conspecifics, are considered to be ideal signals to induce morphological change in aquatic environments rather than close cues, i.e., close chemical or tactile cues, since chemical substances that can propagate over relatively long distances and persist for a long period may allow organisms to keep safe and to deliberately change their morph. In fact, most organisms adopting an inducible morphological defense utilize remote chemical cues to detect predation risk and to produce morphological defenses. In this paper, we report a unique and functionally well designed inducible morphological defense strategy where the induction process requires close cues from a predator. The tadpoles of Rana pirica exhibited a bulgy bodied morphology when threatened with predation by larval salamanders, Hynobius retardatus, in close proximity. Predation trials and a function experiment showed that the induced bulgy morph is an adaptive defense phenotype against the gape-limited predator larval H. retardatus. Furthermore, R. pirica tadpoles use two adaptive strategies in terms of cost saving, i.e., adjustment of the extent of bulginess according to predation risk and reversibility by actual shrink of bulgy body after removing the predation threat. In general, R. pirica hatch earlier than H. retardatus. In natural ponds, during the early developmental stage R. pirica tadpoles live in close proximity to young H. retardatus larvae. As they grow, the salamanders gradually become serious predators and the predator-prey interaction becomes intimate. After a while, predation, cannibalism and metamorphosis decrease the number of salamanders in the ponds, and the predator-prey interaction weakens. Such a phenology in the predator-prey interaction allows the evolution of a close-cue detection system and adaptive cost-saving strategies. Our results highlight that the characteristics of the inducible defense depend on the intensity and specificity of the predator-prey system.
• Coupling of two competitive systems via density dependent migration

  Kinya Nishimura, Osamu Kishida

  ECOLOGICAL RESEARCH 16 3 359 - 368 2001年09月 [査読有り][通常論文]
   

  Coupling of two Lotka-Volterra type competition systems with density-dependent migration was surveyed. We assumed that species x and y are each exclusively superior in subhabitat 1 and subhabitat 2, respectively, and that population densities that exert intra-and interspecific competitive effects also impose pressures for migration of individuals from a subhabitat. If the two species are, respectively, abundant in the subhabitats in which either species is competitively superior, and the migration has a mixing effect, then, it would be intuitively expected that, as potential migration rates increase, the two species are mixed well and coexist in the whole habitat. An analysis of this competitive situation using our model under the assumption of linear diffusion predicted that, even though weak mixing maintains coexistence in the whole habitat, strong mixing collapses coexistence and leads to the exclusion of one species. The assumption that migrations occur due to self- and cross-population pressures provides different predictions: (i) weak dominance and strong mixing destabilize the coexistence state and lead to a monopolizing equilibrium of either species (bistability of monopolizing equiliblia); (ii) conspicuous weakness of the inferior species makes the mixing equilibrium stable, regardless of the potential migration rate; and (iii) tri-stability exists in between situations (i) and (ii). In the third case, the attainable state is the mixing equilibrium or either of the monopolizing equilibria, depending on the initial state. Migration mechanisms with self- and cross-population pressures tends to mediate spatial segregation and makes coexistence possible, even with strong mixing.

MISC

• サクラマスの降河行動におけるサイズ依存性

  二村凌, 菅野陽一郎, 照井慧, 森田健太郎, 奥田篤志, 岸田治 日本生態学会大会講演要旨(Web) 69th 2022年
• 速度をかえるか,期間をかえるか?~降海前サクラマスのサイズ依存的な成長戦術~

  二村凌, 森田健太郎, 菅野陽一郎, 汲川正次, 奥田篤志, 松岡雄一, 杉山弘, 高橋廣行, 高井孝太郎, 内田次郎, 岸田治 日本生態学会大会講演要旨(Web) 68th 2021年
• サクラマスの降海時の行動様式

  二村凌, 森田健太郎, 菅野陽一郎, 岸田治 個体群生態学会大会プログラム・講演要旨集(Web) 37th 2021年
• 北海道に生息するハリガネムシ類の感染経路における終宿主の種多様性効果の検証

  友渕直人, 内海俊介, 太田民久, 岸田治, 舘野隆之輔, 丹羽滋, 長谷川功, 瀧本岳, 森健介, 佐藤拓哉 日本生態学会大会講演要旨(Web) 68th 2021年
• 攻撃的捕食者に対するヤマアカガエル幼生の誘導防御

  後藤俊矢, 清水宏一郎, 岸田治, 阿部晴恵 日本生態学会大会講演要旨(Web) 67th 2020年
• 回遊を成功させるために:サクラマス回遊前のサイズ依存成長戦術

  二村凌, 森田健太郎, 菅野陽一郎, 岸田治 個体群生態学会大会プログラム・講演要旨集(Web) 36th 2020年
• 可塑的形態のリアクションノームの地域変異はRAD‐seqによる集団遺伝情報から読み解けるか

  松波雅俊, 北野潤, 岸田治, 道前洋史, 永野惇, 豊田敦, 藤山秋佐夫, 三浦徹, 西村欣也 日本進化学会大会プログラム・講演要旨集(Web) 20th 105 (WEB ONLY) 2018年08月22日 [査読無し][通常論文]
  
• 北大研究林の強みを活かした教育研究の充実に向けて : 平成27年度年度報告会総合討論

  中路 達郎, 岸田 治, 内海 俊介, 福澤 加里部, 伊藤 悠也, 間宮 春大, 芦谷 大太郎, 上浦 達哉, 小林 真 北方森林保全技術 (34) 43 -47 2017年02月
• エゾサンショウウオにおける表現型可塑性の地域集団比較

  松波雅俊, 北野潤, 岸田治, 道前洋史, 三浦徹, 西村欣也 日本生態学会大会講演要旨(Web) 63th P2‐219 (WEB ONLY) 2016年 [査読無し][通常論文]
  
• 被食者・捕食者によって引き起こされるエゾサンショウウオ幼生の表現型可塑性についてのトランスクリプトーム解析

  松波雅俊, 北野潤, 岸田治, 道前洋史, 三浦徹, 西村欣也 日本進化学会大会プログラム・講演要旨集(Web) 17th ROMBUNNO.2A‐6 (WEB ONLY) 2015年08月20日 [査読無し][通常論文]
  
• 天然更新によるトドマツ人工林複層林化への試み―鋸谷式間伐と樹冠下掻起しの実践―

  坂井励, 吉田俊也, 小塚力, 高木健太郎, 岸田治, 片山昇, 高橋廣行, 浪花愛子, 伊藤欣也, 実吉智香子, 五十嵐満, 和田克法, 大岩敏昭, 永井義隆, 古和田四郎, 小池義信, 椿本勝博, 大岩健一, 佐藤博和, 宮崎徹, 大岩真一, 岡翼 北方森林保全技術 (32) 1 -11 2015年03月23日 [査読無し][通常論文]
  
• 天然更新によるトドマツ人工林複層林化への試み

  坂井励, 吉田俊也, 小塚力, 高木健太郎, 岸田治, 片山昇, 高橋廣行, 浪花愛子, 伊藤欣也, 実吉智香子, 五十嵐満, 和田克法, 大岩敏昭, 永井義隆, 古和田四郎, 小池義信, 椿本勝博, 大岩健一, 佐藤博和, 宮崎徹, 大岩真一, 岡翼 北海道大学総合技術研究会報告集 平成26年度(CD-ROM) 2014年
• トランスクリプトーム解析で迫るエゾサンショウウオの表現型可塑性の分子機構

  松波雅俊, 岸田治, 北野潤, 道前洋史, 三浦徹, 西村欣也 日本生態学会大会講演要旨(Web) 61st D2-08 (WEB ONLY) 2014年 [査読無し][通常論文]
  
• トランスクリプトーム解析で迫るエゾサンショウウオの表現型可塑性の分子機構

  松波雅俊, 岸田治, 北野潤, 道前洋史, 三浦徹, 西村欣也 個体群生態学会大会プログラム・講演要旨集 29th 29 2013年10月11日 [査読無し][通常論文]
  
• ブチサンショウウオ福岡-佐賀県個体群の卵嚢内卵数と胚重量

  手塚 あゆみ, 立脇 康嗣, 岸田 治 爬虫両棲類学会報 2012 (2) 109 -111 2012年09月 [査読無し][通常論文]
  
• 形を変えるオタマジャクシ : 操作実験からのアプローチ

  岸田 治 種生物学研究 35 (0) 11 -52 2012年03月31日 [査読無し][通常論文]
  
• 天塩研究林における育林事業の展開と今後の展望

  小塚 力, 高木 健太郎, 岸田 治 北方森林保全技術 0 (29) 1 -13 2011年11月 [査読無し][通常論文]
  
• 課題研究の進め方の提案 : ドングリとエゾシカの長期モニタリングから

  中村 誠宏, 岸田 治 北方森林保全技術 0 (29) 30 -35 2011年11月 [査読無し][通常論文]
  
• 特集にあたって(<特集1>表現型の可塑性 : その適応的意義の探求)

  岸田 治, 入江 貴博 日本生態学会誌 57 (1) 25 -26 2007年03月31日 [査読無し][通常論文]
  
• 密度依存的移動によって連関した2つの競争系

  西村 欣也, 岸田 治 日本生態学会誌 51 (3) 306 -306 2001年12月20日 [査読無し][通常論文]
  

書籍等出版物

• 多種系における表現型可塑性（分担執筆） シリーズ群集生態学2 進化生物学からせまる

  京都大学学術出版会 2009年

共同研究・競争的資金等の研究課題

• 野生生物における種分化の生態遺伝機構

  日本学術振興会：科学研究費助成事業

  研究期間 : 2022年04月 -2027年03月 

  代表者 : 北野 潤, 岸田 治, 石川 麻乃, 山崎 曜, 山道 真人
• 適応戦術としての動物の移動：河川性サケ科魚類の大規模モニタリングによる検証

  日本学術振興会：科学研究費助成事業

  研究期間 : 2022年04月 -2026年03月 

  代表者 : 岸田 治
• 河川性魚類の行動と生活史の統合戦略：PITタグシステムを駆使した探索的研究

  日本学術振興会：科学研究費助成事業

  研究期間 : 2020年07月 -2022年03月 

  代表者 : 岸田 治, 森田 健太郎

   

  動物個体の移動は，動物の生き様や生態を研究するうえで不可欠である. 本研究では，移動中の動物はいかなる死亡圧にさらされているのか，死亡圧を逃れるためにどのような行動や生活史の戦術があるのかについて, PITタグを用いたサクラマスの個体追跡研究により探索的に調べた. その結果，降海型サクラマスは降河中に下流で小さな個体ほど死にやすいサイズ依存の死亡圧にさらされることが明らかになるとともに，河川下流や海洋でのサイズ依存の死亡圧から逃れるための戦術として，降海型では小さな個体ほど冬季の成長が良く，降河が遅いことで，より大きなサイズになってから川を下ることが明らかとなった．
• サイズダイナミクスの生態学

  文部科学省：科学研究費補助金(基盤研究(B))

  研究期間 : 2017年04月 -2022年03月 

  代表者 : 岸田 治
• 北海道に侵入したアズマヒキガエルが水域の生物 群集に与える影響

  旭硝子財団：旭硝子財団研究助成近藤グラント

  研究期間 : 2017年04月 -2020年03月 

  代表者 : 岸田 治
• 北海道に侵入した強毒性ヒキガエルのインパクト

  三井物産：三井物産環境基金

  研究期間 : 2017年04月 -2020年03月 

  代表者 : 岸田 治
• 複合生態系における寄生者感染動態と群集動態の関係の統合理解

  日本学術振興会：科学研究費助成事業

  研究期間 : 2015年04月 -2018年03月 

  代表者 : 佐藤 拓哉, 渡辺 勝敏, 徳地 直子, 舘野 隆之輔, 金岩 稔, 瀧本 岳, 日浦 勉, 岸田 治, 内海 俊介

   

  寄生者介在型のエネルギー流 (PMEF, Parasite-Mediated Energy Flow) の時間変動性に注目して、PMEFが異なる時間スケールでどのように群集動態に影響を及ぼし、寄生者自身の感染動態にフィードバックするかを実証と理論を統合したアプローチで検証した。地域に応じたハリガネムシ類の種多様性と宿主利用の多様性に依存して、PMEFの時間変動性が規定されていた。野外実験と数理モデルから、PMEFの時間変化に対するサケ科魚類の応答の個体間変異が、群集動態を規定する重要な要因になることが確かめられた。生態系間の季節的な相互作用が群集の形成過程に重要な役割を果たすことが示された。
• 水生動物がアミノ酸を飲む -見落とされていた窒素循環プロセスの解明-

  日本学術振興会：科学研究費助成事業

  研究期間 : 2014年04月 -2016年03月 

  代表者 : 岸田 治, 小林 真

   

  本研究の目的は、「水生動物が溶存アミノ酸をエネルギーとして利用する可能性」を孵化直後のエゾサンショウウオ幼生を用いて示すことである。実験の結果、アミノ酸を添加した環境水で飼育したエゾサンショウウオ幼生は、アミノ酸由来の窒素を体内に取り込み、成長を促進させることが分かった。細菌などの微生物が溶存アミノ酸を直接利用し増殖することは一般に認知されているが、脊椎動物による溶存アミノ酸の利用はこれまで想定されてこなかった。本研究の成果は、「これまでの慣習的な栄養伝達経路の有り様」の変更を促すものである。
• 表現型可塑性：生態学と分子発生学の統合的研究

  日本学術振興会：科学研究費助成事業

  研究期間 : 2011年04月 -2016年03月 

  代表者 : 西村 欣也, 三浦 徹, 岸田 治, 道前 洋史, 北野 准

   

  北海道の固有種であるエゾサンショウウオ(Hynobius retardatus)の幼生は、捕食者生物、餌生物、同種幼生の存在に呼応して生態学的機能を有する表現型可塑性を示す。そのため、進化生態学、発生生物学を融合する研究の優れたモデル生物である。 本研究では、エゾサンショウウオ幼生が捕食者生物存在下、餌生物存在下で可塑的に発現される形態変化について、幾何学的形態解析法を用いて定量的に明らかにし、その分子発生学的メカニズムを調べる出発点として形態変化と関連するゲノム情報の探索を行った。さらに、生息域全域を網羅する５地域集団間で、表現型可塑性に伴う形態変化の反応規範と、遺伝マーカーの変異を調べた。
• 適応的な表現型可塑性間の環境依存的な配分に関する研究

  日本学術振興会：科学研究費助成事業

  研究期間 : 2011年 -2013年 

  代表者 : 道前 洋史, 岸田 治

   

  理論的研究では最適な表現型が環境で異なる（トレードオフの関係がある）とき、すなわち表現型の発現や維持に環境特異的なコストがかかるからこそ必要なときにしか発現しない戦略、表現型可塑性が進化することを示してきた。ところが実証的研究では充分にこの理論は確かめられていない。本研究では表現型のベネフィットやコストを多様な環境で検証することが可塑性の進化の理解に欠かせないことを示した。
• 同所的種内変異が生み出す相互作用と群集レベルの効果

  文部科学省：科学研究費補助金(基盤研究(B))

  研究期間 : 2012年 -2012年 

  代表者 : 岸田 治

   

  同じ種であっても個体によって、生活史や形、行動など様々な形質に違いが見られる。本研究では、同所的にいる同種個体の形質の違いが群集レベルでどのような意味を持つのかについて、両生類を中心とする池の群集をモデルとして、実験的に探索した。捕食者種の形質変異の効果として、ふ化タイミングやサイズの個体間変異が大きいと、共食いが生じサイズ変異が拡大することで、種間相互作用の構造が大きく変わることが分かった。被食者種においても、サイズが異なる同種個体同士が捕食者を介して間接的に関係しあうことが示された。一連の効果は群集の機能と動態に強く影響することから、生態学において形質変異を考慮することの意義が示された。
• エゾヤチネズミ個体群の遺伝的空間構造形成に関わる個体数変動と分散行動の効果

  文部科学省：科学研究費補助金(基盤研究(B))

  研究期間 : 2010年 -2012年 

  代表者 : 齊藤 隆, 石橋 靖幸, 岸田 治

   

  (a)個体群の周期変動と遺伝的距離の関係:石狩湾沿いにある連続した森林にさまざま距離間隔で8調査プロット(0.5ha)を設置し,エゾヤチネズミの標識-再捕獲調査を実施した.プロット間の距離は50-2000mで,さまざま距離間隔で個体群間の遺伝的距離と地理的な距離の関係,個体の分散行動を分析することができる.個体数が石狩地方よりも数倍大きく変動する根室市で石狩地方と類似の調査を行った.捕獲個体数は石狩で約300頭、根室で約500頭に達し,現在DNAを分析している.(b)大きなスケールの個体群構造解析:前課題で収集したエゾヤチネズミのサンプル(1360個体)のmtDNAの分析をほぼ終了し,現在,沿海州のサンプルを含めて地理系統学的な解析を行っている.(c)石狩湾個体群の解析結果:2009年の予備調査で採取したエゾヤチネズミのサンプル(162個体)のmtDNAを解析した結果,雌雄で集団構造に大きな違いがあることが分かった.メスの集団は500m以上離れると相互に遺伝的距離が大きな離れた個体群が見られく,比較的近距離から個体群の独立性が認められた.また,1.5km以上離れると遺伝的に類似していると見なされる集団は見られなくなった.一方,オスには個体群間の地理的距離と遺伝的な距離に明瞭な関係は認められず,個体群相互に遺伝的な交流がある適度保たれていた.これは,オスは良く分散するがメスは出...
• 捕食者-被食者系の形質間相互作用とその進化学・生態学的意義

  文部科学省：科学研究費補助金(若手研究(B))

  研究期間 : 2010年 -2011年 

  代表者 : 岸田 治

   

  エゾサンショウウオ幼生(捕食者)、エゾアカガエルのオタマジャクシ(被食者種1)、ミズムシ(被食者種2)、落葉(オタマジャクシ及びミズムシの餌)からなる生態系をモデルとして、個体の形質変化の生態学的・進化学的意義を探索した。この系では、サンショウウオはオタマジャクシがいるときに捕食に有効な大顎型の形態に変化すること、逆に、オタマジャクシはサンショウウオがいるときに頭部を膨らませた防御形態を発現することが知られている。1.形態変化の生態学的意義:相互作用の改変と生態系機能へのカスケード効果オタマジャクシの防御形態を操作した水槽実験により、「オタマジャクシが防御することで、サンショウウオが栄養価の低いミズムシを高頻度で食うようになり、生き残ったオタマジャクシが落葉の分解を促進することや、サンショウウオの変態が遅れること」を明らかにした。この研究により、被食者の防御適応が、捕食者の生活史や群集を構成する種の個体数に加え、生態系機能にまで影響することが明確に示された。2.形態変化の進化学的意義個体の形質変化が相互作用を変えるのであれば、それは群集構成種の形質選択にも作用すると考えられる。この仮説を検討するために、ミズムシの体サイズ分布に対するサンショウウオの選択圧がオタマジャクシの存在によって異なるのか、実験的に調べた。その結果、「オタマジャクシがいない場合に比べ、オタマジャクシがいる...
• 個体の可塑性と生物群集との相互関係の実証:両棲類幼生の形態変化に注目して

  文部科学省：科学研究費補助金(若手研究(スタートアップ), 研究活動スタート支援)

  研究期間 : 2009年 -2010年 

  代表者 : 岸田 治

   

  変化する生物群集のなかで生物個体は形質をどのように変えるのか?その結果として個体群や群集レベルでどのような帰結がもたらされるのか?個体の応答性と高次の生態学的要素との相互関係の理解は、表現型可塑性研究の新しいムーブメントである。平成21年度は、1.この未開の領域において優先的に取り組まれるべき課題を明らかにするため、捕食者-被食者系の表現型可塑性に関する最近の研究の論点と成果をまとめた。その結果、(1)3種以上の相互作用系での個体の形質変化、(2)複数の誘導形質間の発現・機能上の関係性、(3)捕食者の可塑性による相互作用強度の変更、(4)捕食者と被食者の対抗性とその生態学的な影響、等のトピックについての理解が不足していることがわかった。そこでこれらについて理論的・実証的に研究する方法を提案した(以上は、総説論文として、Population Ecology誌に公表した)。2.次にトピック(4)に関する理論的研究を行った。捕食者と被食者の対抗的な可塑性の進化動態と個体群動態を数学的にモデル化し解析したところ、被食者が効果的な防御をもつときに捕食者と被食者の対抗的な可塑性が共進化しやすく、2種の個体群動態が安定的に持続することが分かった。3.最後に、個体の可塑性の群集生態学的影響を定量的に評価するためのモデル実験系を確立した。報告者はこれまでに可塑性研究の有効なモデル系として、エゾ...
• Evolutionary Ecology of Phenotypic Plasticity in Amphibian Larvae.