Faculty Profiles - Ohkubo Yusaku

Papers - Ohkubo Yusaku

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Causal and predictive data analysis for conservation: a case study for detecting impact of artificial feeding on Eurasian red squirrel (Sciurus vulgaris)

Yusaku Ohkubo, Ozora Takeda, Kenta Uchida

2025.4

Hereditary nature of death-feigning frequency in a parasitoid wasp Heterospilus prosopidis using sib analysis Reviewed

Haruna Fujioka, Takahisa Miyatake, Yusaku Ohkubo, Masakazu Shimada

Journal of Evolutionary Biology 2024.6

Publishing type：Research paper (scientific journal) Publisher：Oxford University Press (OUP)

Abstract

Death feigning, a state of immobility observed in many animals in response to external stimuli, is an anti-predator behaviour. Although previous studies showed that death-feigning behaviours are quantitative genetic traits, the knowledge of the heritable basis of death-feigning behaviour is lacking. To investigate the heritable basis of death-feigning behaviour, we used 3 laboratory strains of a braconid parasitoid wasp, Heterospilus prosopidis. The heritable basis using half-sib analysis, and the effects of different geographical backgrounds, rearing conditions in the laboratory, and host age were evaluated. The results of the half-sib analysis showed that the frequency of death feigning varied among sires, suggesting a certain extent of additive genetic variance. Also, the frequency of death feigning varied between geographical backgrounds and among strains. Death-feigning frequency was not affected by the age of the host. Our findings highlight the importance of genetic factors underlying the basis of the death-feigning behaviour and provide support for the genetic alterations of traits from the perspective of evolution in various animal species.

DOI： 10.1093/jeb/voae079

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Foraging predicts the evolution of warning coloration and mimicry in snakes Reviewed

Yosuke Kojima, Ryosuke K. Ito, Ibuki Fukuyama, Yusaku Ohkubo, Andrew M. Durso

Proceedings of the National Academy of Sciences 2024.3

Heritable effects on caste determination and colony-level sex allocation in termites under field conditions Reviewed

Mamoru Takata, Shuya Nagai, Tatsuya Inagaki, Yusaku Ohkubo, Eisuke Tasaki, Kenji Matsuura

iScience 26 ( 3 ) 106207 - 106207 2023.3

A novel phylogenetic comparative method for evaluating the strength of branch-specific directional selection Reviewed

Yusaku Ohkubo, Nobuyuki Kutsukake, Itsuro Koizumi

Evolution 77 ( 1 ) 63 - 82 2022.12

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Oxford University Press (OUP)

Abstract

Phylogenetic comparative methods (PCMs) have played a central role in studying the evolution of phenotypic traits. However, when a trait experienced directional selection, previous PCMs have faced a dilemma between mathematically tractable but restrictive models (i.e., simple Gaussian process models) and flexible but intractable approaches (i.e., a simulation-based process model of phenotype evolution built on population genetics frameworks). This paper proposes a novel Gaussian process macroevolutionary model, called the “branch-specific directional selection (BSDS),” for evaluating the strength of directional selection to reconcile these two approaches. This model is based on a second-order approximation of a previous simulation-based process model but has a closed-form likelihood function. This can also be extended to incorporate intraspecies variations and to linear mixed models, which are necessary for meta-analysis. We conduct numerical experiments to validate the proposed method and apply it to the brain volume of Hominidae species. The results show that the proposed methods yield statistically more reliable inferences and computational time is about hundred thousand times faster than the previous simulation-based methods. Further extensions of the BSDS model are expected to provide a clearer picture of the connection of microevolutionary processes and macroevolutionary patterns.

DOI： 10.1093/evolut/qpac015

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Spillover and spillback risks of ectoparasites by an invasive squirrel Callosciurus erythraeus in Kanto region of Japan Reviewed

Hirotaka Katahira, Yuya Eguchi, Saki Hirose, Yukino Ohtani, Azusa Banzai, Yusaku Ohkubo, Tatsuki Shimamoto

International Journal for Parasitology: Parasites and Wildlife 19 1 - 8 2022.12