Mathematical Biology Laboratory Department of Biology, Kyushu University

Ryo Yamaguchi

NAME

Ryo Yamaguchi

Email: ryamaguchi[at]bio-math10.biology.kyushu-u.ac.jp
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CURRENT POSITION

Ph.D. candidate, Graduate School of Systems Life Sciences, Kyushu University
Japan Society for the Promotion of Science for Young Scientists, DC1

EDUCATION

  • B.S. Kyushu University, Japan, 2012 (Biology)
  • M.S. Kyushu University, Japan, 2014 (Mathematical Biology)

RESEARCH INTERESTS

Species diversity is explained by the balance between speciation and extinction and, consequently, speciation is a central topic of evolutionary science. In spite of a commonly accepted view that many species originated through allopatric divergence, it is also widely considered such an obvious process that it is ‘theoretically trivial’. My previous research analyzes the waiting time to an early stage of allopatric speciation especially including successful rare migration events. Assuming that geographical isolation and population subdivision proceed gradually, this is more supposable situation than expected before. Current research theme is reproductive character displacement by reproductive interference, which also results in evolution of prezygotic isolation. Moreover, to inspire my theoretical research, I am working on morphology and phylogeny about one of the butterfly groups Faunis menado (Morphinae, Nymphalidea) including 9 subspecies in Sulawesi island.

PUBLICATIONS

(10) R. Yamaguchi, Y. Iwasa. A tipping point in parapatric speciation. Journal of Theoretical Biology. (accepted).
(9) R. Yamaguchi, Y. Iwasa. Parapatric speciation in three islands: dynamics of geographic configurations of allele sharing. Royal Society Open Science. 4: 160819. 2017.
(8) R. Yamaguchi, S. Suefuji, K. Odagiri, O. Yata. The endemic Sulawesi amathusiine Faunis menado Hewitson (Lepidoptera, Nymphalidae) is divisible into two morphospecies. Lepidoptera Science. 67(1): 12-21. 2016.
(7) R. Yamaguchi, Y. Iwasa. Smallness of the number of loci can facilitate parapatric speciation. Journal of Theoretical Biology. 405: 36-45. 2016.
[6] R. Yamaguchi, Y. Iwasa. Reproductive interference can promote recurrent speciation. Population Ecology DOI: 10.1007/s10144-015-0485-2. 2015.
[5] R. Yamaguchi, Y. Iwasa. First passage time to allopatric speciation, for a contribution to a special issue of "Modelling biological evolution: recent progress, current challenges and future direction". Interface Focus. 3(6): 20130026. 2013.
[4] R. Yamaguchi, Y. Iwasa. Reproductive character displacement by the evolution of female mate choice. Evolutionary Ecology Research. 15: 25-41. 2013.
[3] R. Yamaguchi. A brief note on Amathusiini in Sulawesi. The Nature and Insects. Vol. 50(4): 4-8. 2015.
[2] R. Yamaguchi, S. Suefuji, K. Odagiri. Taxonomic reexamination of Faunis menado. The Nature and Insects. Vol.48(10): 28-31. 2013.
[1] R. Yamaguchi. Butterfly fauna of South-Central Sulawesi, Indonesia, The Nature and Insects. Vol.47(3): 25-29. 2012.

Hiroki Ikeda

NAME

Hiroki Ikeda

Email: hiro_shun_sparklings[at]yahoo.co.jp
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CURRENT POSITION

Ph.D. candidate, Graduate School of Systems Life Sciences, Kyushu University
Japan Society for the Promotion of Science for Young Scientists, DC1

EDUCATION

  • B.S. Kyushu University, Japan, 2013 (Biology)
  • M.S. Kyushu University, Japan, 2015 (Mathematical Biology)

PROFESSIONAL EXPERIENCE

  • Japan Society for the Promotion of Science for Young Scientists, DC1 (2015.4-2018.3)

RESEARCH INTERESTS

[1] Viral infection dynamics (HIV, SHIV, HCV, Infulenza)
[2] Mathematical modeling and quantifying for viral infection
[3] Structuring of theory for viral infection model
[4] Evolutional virology

PUBLICATIONS

[4] H. Ikeda, A. Godinho-Santos, S. Rato, B. Vanwalscappel, F. Clavel, K. Aihara, S. Iwami, and F. Mammano. Quantifying the antiviral effect of IFN on HIV-1 replication in cell culture, Scientific Reports. 5:11761 (2015).
[3] Hiroki Ikeda, Shinji Nakaoka, Kei Sato, Naoko Misawa, Yoshio Koyanagi, and Shingo Iwami. Effect of eclipse phase on quantifying viral dynamics of acute HIV-1 infection in humanized mouse model, Nonlinear Theory and Its Applications, IEICE Vol. 6 (2015) No. 1 pp. 47-53
[2] Ikeda H, de Boer RJ, Sato K, Morita S, Misawa N, Koyanagi Y, Aihara K, and Iwami S. Improving the estimation of the death rate of infected cells from time course data during the acute phase of virus infections: application to acute HIV-1 infection in a humanized mouse model, Theor Biol Med Model. 11:22 (2014)
[1] Iwami S, Koizumi Y, Ikeda H, and Kakizoe Y. Quantification of viral infection dynamics in animal experiments, Front Microbiol. 4:264 (2013)

Yuki Kubo

NAME

Yuki Kubo

Email: yukikubo[at]kyudai.jp
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Personal website: yukikubo.com

CURRENT POSITION

Ph.D. candidate, Graduate School of Systems Life Sciences, Kyushu University
Japan Society for the Promotion of Science for Young Scientists, DC1

EDUCATION

  • B.S. Kyushu University, Japan, 2013 (Biology)
  • M.S. Kyushu University, Japan, 2015 (Mathematical Biology)

RESEARCH INTERESTS

[1] Animal Collective Behaviour
[2] Plantation management in tropical forests, especially Indonesia
[3] Decision making process

PUBLICATIONS

[1] Y. Kubo, and Y. Iwasa. Phase diagram of a multiple forces model for animal group formation: marches versus circles determined by the relative strength of alignment and cohesion. Population Ecology (2016).

Makoto Douge

NAME

Makoto douge

Email: makotodouge[at]gmail.com
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CURRENT POSITION

Ph.D. candidate, Graduate School of Systems Life Sciences, Kyushu University

EDUCATION

  • B.S. Hitotsubashi University, Japan, 1974 (Low)
  • M.S. The Open University of Japan, 2015 (Biology)

RESEARCH INTERESTS

I study the reason of sexual reproduction by computer simulation.

Kenji Yoshida

NAME

Kenji Yoshida

Email: false_saffron[at]yahoo.co.jp
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CURRENT POSITION

Ph.D. candidate, Graduate School of Systems Life Sciences, Kyushu University

EDUCATION

  • B.S. Kyushu University, Japan, 2013 (Biology)

Yusuke Kakizoe

NAME

Yusuke Kakizoe

Email: yusuke.purple5[at]gmail.com
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CURRENT POSITION

Ph.D. candidate, Graduate School of Systems Life Sciences, Kyushu University
Japan Society for the Promotion of Science for Young Scientists, DC1

EDUCATION

  • B.S. Kyushu University, Japan, 2014 (Biology)
  • M.S. Kyushu University, Japan, 2016 (Mathematical Biology)

Shinsuke Satoi

NAME

Shinsuke Satoi

Email: ssatoi257n[at]gmail.com
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CURRENT POSITION

Ph.D. candidate, Graduate School of Systems Life Sciences, Kyushu University
Japan Society for the Promotion of Science for Young Scientists, DC1

EDUCATION

  • B.S. Kyushu University, Japan, 2014 (Biology)
  • M.S. Kyushu University, Japan, 2016 (Mathematical Biology)

RESEARCH INTERESTS

Leuckart’s Law states that among vertebrates, swifter animals should have larger eyes. A positive correlation between movement speed and eye size is a plausible hypothesis because faster-moving animals need to have a higher level of visual acuity to recognize food items and obstacles while they are still far away and because the ability of eyes to resolve images is known to increase with their size. A small number of empirical studies suggest that Leuckart’s Law is supported for mammals but rejected for birds. To better understand the conditions under which Leuckart’s Law holds, we conducted computer simulations of an animal moving on a plane that contains many food items as well as obstacles. The animal moves at a constant speed but changes its directional angle when it recognizes food items or obstacles. We examined the number of food items the animal consumed and the number of obstacles it collided with. Given a small cost of visual acuity, we obtained the optimal visual acuity, which depended on several parameters such as visible distance, visible angle, turning ability, movement speed, and densities of foods and obstacles in the field. Assuming that the animal’s visual acuity is close to the optimal value predicted by the model, Leuckart’s Law mostly holds when animals are in an environment with similar densities of food items and obstacles. The positive correlation between movement speed and visual distance was stronger with more obstacles and fewer food items. However, Leuckart’s Law may not hold if food is abundant, obstacles are rare, and collision damage is small.

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