* corresponding author, underline lab member


  • Ishiyama N, Sueyoshi M, Jorge GM, Iwasaki K, Negishi J, Koizumi I, Nagasaka A, Nagasaka Y. and Nakamura F. Underlying geology and climate interactively shape climate change refugia in mountain streams. Ecological Monographs (in press)
  • Hasegawa R and Koizumi I (2023) Parasites either reduce or increase host vulnerability to fishing: a case study of a parasitic copepod and its salmonid host. The Science of Nature – Naturwissenschaften, 110, 10
  • Masuda T, Shimono Y, Kishi D, and Koizumi I (2023) Systematic headwater sampling of white-spotted charr reveals stream capture events across dynamic topography. Journal of Biogeography, 50, 453-466 *Selected as Editor’s Choice! (Free Open Access!)
  • Ohkubo Y, Kutsukake N and Koizumi I (2023) A novel phylogenetic comparative method for evaluating the strength of branch-specific directional selection. Evolution, 77, 63-82


  • Anders JL, Mychajliw AM, Moustafa MAM, Mohamed WMA, Hayakawa T, Nakao R, and Koizumi I. (2022) Dietary niche breadth influences the effects of urbanization on the gut microbiota of sympatric rodents. Ecology and Evolution, 12, e9216
  • Hasegawa R, Katahira H and Koizumi I (2022) Salmincola markewitschi (Copepoda: Lernaeopodidae) orS. carpionis? A requirement for taxonomic revision due to their high morphological variations. Folia Parasitologica, 69, 025
  • Hasegawa R, Ayer CG, Umatani Y, Miura K, Ukumura M, Katahira H and Koizumi I (2022) Potential negative effects and heterogeneous distribution of a parasitic copepod Salmincola edwardsii (Copepoda: Lernaeopodidae) on Southern Asian Dolly Varden Salvelinus curilus in Hokkaido, Japan. Parasitology International, 87, 102529
  • Ayer CG, Morita K, Fukui S and Koizumi I (2022) No apparent effects of the buccal cavity attaching parasite, Salmincola sp. (Copepoda: Lernaeopodidae), on a stream salmonid: a mark-recapture study. Ichthyological Research, 69, 261–266
  • Furusawa C, Kanazawa-Suehiro Y, Tanaka Y, Fukui S, Yamazaki C, Hosoki TK, Koizumi I* (2022) Local factors affecting winter habitat use of nonnative rainbow trout in a boreal stream in northern Japan. Ichthyological Research, 69, 125-131 *Editor’s Choice Selected as Editor’s Choice! (Free Open Access!) 


  • Anders JL, Moustafa MAM, Mohamed WMA, Hayakawa T, Nakao R, and Koizumi I (2021) Comparing the gut microbiome along the gastrointestinal tract of three sympatric species of wild rodents. Scientific Reports, 11, 19929
  • Hasegawa R and Koizumi I (2021) Relative importance of host dependent vs. physical environmental characteristics affecting the distribution of an ectoparasitic copepod infecting to the mouth cavity of stream salmonid. Ecological Research, 36, 1015-1027
  • Chow PKA, Uchida K, von Bayern A and Koizumi I (2021) Characteristics of urban environments and novel problem-solving performance in Eurasian red squirrels. Proceedings of the Royal Society B, 288, 20202832 *国内外の多くのメディアに取り上げられました!
  • Zhang Z, Kass J, Mammola S, Koizumi I, Tanaka K, Ikeda K, Suzuki T, Yokota M, and Usio N (2021) ddi13263-toc-0001-mLineage-level distribution models lead to more realistic climate change predictions for a threatened crayfish. Diversity and Distributions, 27, 684-695 *表紙を飾りました!
  • Fukui S, Kasugai K, Sawada A and Koizumi I (2020) Evidence for introgressive hybridization between native Dolly Varden Salvelinus curilus (syn. Salvelinus malma) and introduced brook trout Salvelinus fontinalis in the Nishibetsu River of Hokkaido, Japan. Zoological Science38, 247-251 *北海道新聞などで取り上げて頂きました!
  • Suzuki K, Ishiyama N*, Koizumi I, and Nakamura F (2021) Combined effects of summer water temperature and current velocity on the distribution of a cold-water-adopted sculpin Cottus nozawae. Water, 13, 975
  • Uchida K, Yamazaki T, Okubo Y and Yanagawa H (2021) Do green park characteristics influence human-wildlife distance in arboreal squirrels? Urban Forestry & Urban Greening, 58, 126952
  • Atsumi K, Lagisz M and Nakagawa S (2021) Non-additive genetic effects induce novel phenotypic distributions in male mating traits of F1 hybrids. Evolution, 75, 1304-1315


  • Nakano S, Fausch KD*, Koizumi I, Kanno Y, Taniguchi Y, Kitano S and Miyake Y (2020) Evaluating a pattern of ecological character displacement: charr jaw morphology and diet diverge in sympatry vs. allopatry across catchments in Hokkaido, Japan. Biological Journal of the Linnean Society, 129, 356-378  *解説記事を書きました!
  • Uchida K*, Shimamoto T, Yanagawa H and Koizumi I* (2020) Comparison of multiple behavioral traits between urban and rural squirrels. Urban Ecosystems, 23, 745-754
  • Atsumi K and Koizumi I (2020) Are bolder individuals more likely to choose heterospecific mates? A test in cyprinid fishes. Journal of Ethology, 38, 247-251
  • Fukui S and Koizumi I (2020) Hybrids as potential mediators spreading non-native genes: comparison of survival, growth, and movement among native, nonnative and hybrid salmonids. Ecology of Freshwater Fish, 29, 280-288
  • Yamada T, Koizumi I, Urabe H and Nakamura F (2020) Temperature-dependent swimming performance differs by species: implications for condition-specific competition between stream salmonids. Zoological Science, 37, 429-433
  • Shimamoto T, Uchida K, Koizumi I, Matsui M and Yanagawa H (2020) No evidence of physiological stress in an urban animal: comparison of fecal cortisol metabolites between urban and rural Eurasian red squirrels. Ecological Research, 35, 2ヒグマ学43-251
  • 小泉逸郎(2020)想像を超えたヒグマとサケの繋がり:互いに影響する生態と進化、そして生態系全体へ In:「ヒグマ学への招待」北海道大学出版会 pp 67-86
  • 小泉逸郎(2020)「動物の個性」研究のすすめ:いくつかの注意点.
    日本生態学会誌, 70, 65-70
  • 渥美圭佑(2020)「動物の個性研究」を俯瞰する.日本生態学会誌,
    70, 33-44


    • Uchida K*, Suzuki KK, Shimamoto T, Yanagawa H and Koizumi I* (2019) Reduced vigilance or habituation to humans? Mechanisms on the increased boldness in urban animals. Behavioral Ecology, 30, 1583-1590
    • Watz JR, Otsuki Y, Nagatsuka K, Hasegawa K and Koizumi I (2019) Temperature-dependent competition between juvenile salmonids in small streams. Freshwater Biology, 64, 1534-1541
    • Atsumi K, Kishida O and Koizumi I (2019) Visual preference of males for conspecific mates in mutually ornamented fish: possible support for the species recognition hypothesis. Journal of Ethology, 37, 353-362
    • Anders J, Nakao M, Uchida K, Ayer CG, Asakawa M and Koizumi I (2019) Comparison of the intestinal helminth community of the large Japanese field mouse (Apodemus speciosus) between urban, rural, and natural sites in Hokkaido, Japan. Parasitology International, 70, 51-5
    • Yuta T and Nomi D (2019) Breeding biology of Eurasian nuthatches in northern Japan. Yamashina Institute of Ornithology, 51, 62-67
    • Miura K, Ishiyama N, Kawajiri K, Atsumi K, Tachibana M, Nagasaka Y, Machida Y, Negishi J, Koizumi I and Nakamura F (2019) Simple non-lethal identification criteria for two endangered freshwater pearl mussels, Margaritifera laevis and Margaritifera togakushiensis, in Hokkaido, northern Japan. Ecological Research, 34, 667-677
    • Trout-and-Char-cover
    • Whiteley AR, Penaluna BE, Taylor EB, Weiss S, Abadia-Cardoso A, Gomez-Uchida D, Koizumi I, Trotter P (2019 Trout and char: taxonomy, systematics, and phylogeography. In Kershner et al. (eds.) Trout and Char of the World, American Fisheries Society, pp. 95-140
    • Muhlfeld CC, Dauwalter DC, D’Angelo VS, Ferguson A, Glersch J, Impson D, Koizumi I, Kovach RP, Schoeffmann J and Epifanio J (2019) Global status of freshwater trout and char: conservation challenges in the 21st century. In Kershner et al. (eds.) Trout and Char of the World, American Fisheries Society, pp. 717-760
    • 立木佑弥・堀田淳之介・小泉逸郎. (2019)代替生活史戦術と個体群動態ー行動学的基盤の視点からー In:「遺伝子・多様性・循環の科学: 生態学の領域融合へ」(門脇浩明・立木佑弥編)京都大学学術出版会 pp 91-110


  • Yuta T, Nomi D, Ihle M and Koizumi I (2018) Simulated hatching failure predicts female plasticity in extra-pair behavior over successive broods. Behavioral Ecology, 29, 1264-1270
  • Fukui S, May-McNally S, Taylor EB and Koizumi I (2018) Maladaptive secondary sexual characteristics reduce the reproductive success of hybrids between native and non-native salmonids. Ecology and Evolution, 8, 12173-12182
  • Nomi D, Yuta T and Koizumi I (2018a) Male feeding contribution facilitates multiple brooding in a biparental songbird. IBIS, 160, 293-300
  • Nomi DYuta T and Koizumi I (2018b) Facultative multiple breeding as a female conditional strategy in Japanese tits: partner’s quality affects the initiation of second clutches. Ecological Research, 33, 479-485
  • Nomi DYuta T and Koizumi I (2018c) Seasonal change of sexual differences in nestling size and survival: a framework to evaluate sex-dependent environmental sensitivity in the wild. Avian Research, 9:10
  • Atsumi K, Nomoto K, Machida Y, Ichimura M, and Koizumi I (2018) No reduction of hatching rates among F1 hybrids of naturally hybridizing three Far Eastern daces, genus Tribolodon (Cypriniformes, Cyprinidae)Ichthyological Research, 65, 165-167
  • Ayer C, Katahira H, Fukui S and Koizumi I (2018) Seasonal patterns of downstream movement in partially migratory stream-dwelling Dolly Varden. Ecology of Freshwater Fish, 27, 247-254
  • umbrellaYamaura Y, Higa M, Senzaki M, and Koizumi I (2018) Can charismatic megafauna be surrogate species for biodiversity conservation? mechanisms and a test using citizen data and a hierarchical community model. In: Nakamura F (Ed.) Biodiversity Conservation Using Umbrella Species: Blakiston’s Fish Owl and Red-Crowned Crane, Springer, pp.151-179
  • 乃美大佑 (2018) 繁殖開始のタイミングを決める至近および究極的な要因.
    In:「鳥類の生活史と環境適応」 北海道大学出版会, pp.43-59


  • Atsumi K and Koizumi I (in press) Early maturation of rosyface dace, Tribolodon sachalinensis (Cyprinidae, Cypriniformes) in a small isolated population Biogeography
  • Yamazaki C and Koizumi I* (2017) High frequency of mating without egg release in highly promiscuous nonparasitic lamprey Lethenteron kessleri. Journal of Ethology, 35, 237-243
  • Koizumi I, Tanaka Y and Kanazawa Y (2017) Mass immigration of juvenile fishes into a small, once-dried tributary demonstrates the importance of remnant tributaries as wintering habitats. Ichthyological Research, 64, 353-356
  • Koizumi I, Kanazawa Y, Yamazaki C, Tanaka Y and Takaya K (2017) Extreme winter aggregation of invasive rainbow trout in small tributaries: implications for effective control. Ichthyological Research, 64, 197-203
  • Katahira H, Yamazaki C, Fukui S, Ayer CG and Koizumi I (2017) Spatial aggregation in small spring-fed tributaries leads to a potential metapopulation structure in a parasitic fish leech. Parasitology Open, 3, e11
  • Anders J, Uchida K, Watanabe M, Tanio I, Shimamoto T, Hamada M, Yanagawa H and Koizumi I (2017) Usefulness and limitation of a tiny light-temperature logger to monitor daily activity levels of arboreal squirrels in temperate areas. Mammal Research, 62, 397-404
  • Uchida K, Suzuki K, Shimamoto T, Yanagawa H and Koizumi I (2017) Escaping height in a tree represents a potential indicator of fearfulness in arboreal squirrels. Mammal Study, 42, 39-43
  • Nomi D, Yuta T and Koizumi I (2017) Breeding biology of four sympatric tits in northern Japan.Wilson Journal of Ornithology, 129, 294-300


  • Koizumi I and Shimatani IK (2016) Socially induced reproductive synchrony in a salmonid: an approximate Bayesian computation approach. Behavioral Ecology, 27, 1386-1396
  • Tachiki Y and Koizumi I (2016) Absolute vs. relative assessments of individual status in status-dependent strategies under stochastic environments. The American Naturalist, 188, 113-123
  • Yuta T and Koizumi I (2016) Does nest predation risk affect the frequency of extra-pair paternity in a socially monogamous passerine? Journal of Avian Biology, 47, 153-158
  • Uchida K, Suzuki K, Shimamoto T, Yanagawa H and Koizumi I. (2016) Seasonal variation of flight initiation distance in Eurasian red squirrels in urban versus rural habitat. Journal of Zoology, 298, 225-231
  • Fukui S, May-McNally S, Katahira H, Kitano S and Koizumi I* (2016) Temporal change in the distribution and composition of native, introduced, and hybrid charrs in northern Japan. Hydrobiologia, 783, 309-316
  • Ikeda T, Uchida K, Matsuura Y, Takahashi H, Yoshida T, Kaji K and Koizumi I. (2016) Seasonal and diel activity patterns of eight sympatric mammals in northern Japan revealed by an intensive camera-trap survey. PLoS ONE, 11(10): e0163602
  • Higa M, Yamaura Y, Senzaki M, Koizumi I, Takenaka T, Masatomi Y and Momose K (2016) Scale dependency of two endangered charismatic species as biodiversity surrogates. Biodiversity and Conservation, 25, 1829-1841
  • 池田敬, 内田健太, 渋谷未央, 大熊勳, 石橋悠樹, 嶌本樹, 片平浩孝(2016)「哺乳類研究交流会」の開催報告―学生のステップアップの場として―. 哺乳類科学, 56: 53-60
  • 油田照秋(2016)鳥類の配偶システムとつがい外父性.In:「鳥の行動生態学」 北海道大学出版会, pp.45-75


  • Ayer CG and Katahira H (2015) Crepidostomum spp. (Trematoda: Allocreadiidae) from Sakhalin sticklebacks Pungitius tymensis (Gasterosteiformes: Gasterosteidae) in Eastern Hokkaido, Japan: a new host record of CchaenogobiiBiogeography, 17, 21-28
  • Nomi D, Yuta T and Koizumi I. (2015) Offspring sex ratio of Japanese Tits Parus minor is related to laying date and clutch size only in the first clutches. Acta Ornithologica, 50, 213-220
  • Toyama M., Kotaka N. and Koizumi I. (2015) Breeding timing and nest predation rate of sympatric scops owls with different dietary niche breadth. Canadian Journal of Zoology, 93, 841-847
  • Harris LN, Bajno R, Gallagher CP, Koizumi I, Johnson L, Taylor EB and Reist JD. (2015) Life-history characteristics and landscape attributes as drivers of genetic variation, gene flow and fine-scale population structure in Northern Dolly Varden Char (Salvelinus malma malma) in Canada. Canadian Journal of Fisheries and Aquatic Science, 72, 1477-1493
  • Ishiyama N, Koizumi I, Yuta T and Nakamura F. (2015) Differential effects of spatial network structure and scale on population size and genetic diversity of the ninespine stickleback in a remnant wetland system. Freshwater Biology, 60, 733-744
  • Higa M, Yamaura Y, Koizumi I, Yabuhara Y, Senzaki M and Ono S. (2015) Mapping large-scale bird distributions using occupancy models and citizen data with spatially biased sampling effort.Diversity and Distributions, 21, 46-54
  • 佐藤真理・小泉逸郎(2015)魚類から骨細胞の謎に迫る:ラボとフィールドからの挑戦.細胞 47: 513-516


  • Negishi JN, Soga M, Ishiyama N, Suzuki N, Yuta T, Sueyoshi M., Yamazaki C, Koizumi I, Mizugaki S, Hayashida K, Nunokawa M. and Yoshimura N. (2014) Geomorphic legacy controls macrophyte distribution within and across disconnected floodplain lakes. Freshwater Biology, 59, 942-954
  • Kobayashi F, Toyama M. and Koizumi I* (2014) Potential resource competition between an invasive mammal and native birds: overlap in tree cavity preferences of feral raccoons and Ural owls.Biological Invasions, 16, 1453-1464.
  • Hashimoto S, Koizumi I*, Takai K and Higashi S (2014) Different habitat salinity between two divergent groups of a worm-like goby Luciogobius guttatus: an indication of cryptic species.Environmental Biology of Fishes, 97, 1169-1177
  • Kitano S, Ohdachi S, Koizumi I and Hasegawa K (2014) Hybridization between native white-spotted charr and nonnative brook trout in the upper Sorachi River, Hokkaido, Japan. Ichthyological Research, 61, 1-8
  • Soga M., Ishiyama N., Sueyoshi M., Yamaura Y., Hayashida K., Koizumi I., Negishi J.N. (2014) Interaction between patch area and shape: ponds with different formation processes have contrasting area and shape effects on macrophyte diversity. Landscape & Ecological Engineering, 10, 55-64
  • 坂本洋典・森照貴・小泉逸郎.(2014)温泉・地熱地帯は生物多様性のホットスポットか? 生物科学, 65, 245-255


  • 池田啓・小泉逸郎(編).2013.「系統地理学:DNAで解き明かす生ものの自然史」 文一総合出版社 pp 314
  • 小泉逸郎・池田啓.2013.系統地理学の歴史と展望 In:「系統地理学:DNAで解き明かす生ものの自然史」文一総合出版社 pp 7-32
  • 小泉逸郎.2013. ニホンザリガニのDNAに刻まれた北日本の地史:歴史遺産としての遺伝的多様性 In:「系統地理学:DNAで解き明かす生ものの自然史」文一総合出版社 pp 35-60


  • Koizumi I., Usio N., Kawai T., Azuma N. and Masuda R. (2012) Loss of genetic diversity means loss of geological information: the endangered Japanese crayfish possessed remarkable historical footprints. PLoS ONE, 7, e33986.
  • Koizumi I., Hasegawa K. and Kishi D. (2012) Do small tributaries function as refuges from floods? A test in a salmonid-dominated mountainous river. Ecology of Freshwater Fish, 21, 165-167
  • Yuta T. and Koizumi I. (2012) Long breeding season and high frequency of multiple brooding in Great Tits in northern Japan. ARDEA, 100, 197-201
  • Kitanishi S., Yamamoto T., Koizumi I., Dunham J.B. and Higashi S. (2012) Relationship between sex, life history and dispersal of masu salmon at microgeographic scale. Ecology and Evolution, 2, 920-929


  • Koizumi I. (2011) Integration of ecology, demography and genetics to reveal population structure and persistence: a mini review and case study of stream-dwelling Dolly Varden. Ecology of Freshwater Fish, 20, 352-363
  • Azuma N., Usio N., Korenaga T., Koizumi I., and Takamura N. (2011) Genetic population structure of the invasive signal crayfish Pacifastacus leniusculus in Japan inferred from newly developed microsatellite markers. Plankton & Benthos Research, 6, 179-186