Kotaro Kagawa, Ph.D of Science.
Postdoctoral fellow
Center for Ecology, Evolution & Biogeochemistry, Swiss Federal Institute of Aquatic Science and Technology (Eawag)

Research Interest

The main question of my study is "How did the huge biodiversity on the earth evolved?" To approach the mechanisms underlying evolution of biodiversity, I am using individual-based computer simulation model and mathematical model.

Evolutionary Diversification in Plant-Pollinator Mutualisms

My particular interest is in evolution of diversity in plant-pollinator mutualistic systems. Plants and their pollinator animals show abundant diversity both in the number of species and in the forme of interactons. By using computer simulation models, I am explorling the evolutionary mechanisms underlying the diversity in plant-pollinator mutualisms. In particular, I am studying the following two themes:

(1) What is the role of predators of pollinators in evolutionary diversification in plant-pollinator mutualisms?
Predators of pollinators such as crab spiders are very common. How these "antagonists" of plant-pollinator mutualisms affect evolutionary diversification in plant-pollinator mutualisms? My computer simulation suggested that predators drives active "co-evolutionary" dynamics in plants-pollinator-predator ecosystems. In the simulation, this co-evolutionary dynamics dramatically increased the possibility of evolutionary diversification in plant-pollinator mutualisms. This result suggest that antagonist of mutualisms is also a driver of diversification in plant-pollinator mutualisms.

(2)Why and how flower color polymorphisms in nectarless plant species evolved?
Typically, pollinator animas of plants carry pollen from flowers and gain nectar from flowers as a reward. However, some plant species produce nectarless flower and deceive their pollinators. In some of these nectarless flower species, flower trait polymorphism (e.g. color polymorphism) within species have been observed. Why and how these trait polymorphism evolved? By using computer simulation model, I am investigating evolution of flower triats in nectarless flowers in the context of plant-pollinator interactions.

Which Traits Promote Adaptive Radiation?

There are a lot of animals and plants on the earth. Species richness within phylogenetic group varies between groups. What is the determinant of species richness within phylogenetic groups? In other words, which traits of animals and plants promote diversification of themselves? To approach this question, I am investigating adaptive radiation in computer simulation.

Publications/ Presentations

Research articles

Kagawa, K., Takimoto, G. 2014. Predation on pollinators promotes co-evolutionary divergence in plant-pollinator mutualisms. American Naturalist 183: 229-242.

Takahashi, Y., Kagawa, K., Svensson, E. I., Kawata, M. 2014. Evolution of increased phenotypic diversity enhances population performance by reducing sexual harassment in damselflies. Nature Communications 5: 4468.

Kagawa, K., Takimoto, G. 2016. Inaccurate color discrimination by pollinators promotes evolution of discrete color polymorphism in food-deceptive flowers. American Naturalist in press.

Kagawa, K., Takimoto, G. 2012. How are novel traits evolve? New insights from theoretical studies (in Japanese). The 28th Annual Meeting of Society of Population Ecology, S4, Funabashi, Chiba, Japan.

Suzuki, M., Kagawa, K. 2014. Understanding plant evolution from animal cognitive behavior: toward coevolution of plant ecology and behavioral ecology. (in Japanese) The 61th Annual Meeting of Ecological Society of Japan, W03, Hiroshima, Japan.

Presentations at scientific meetings

Kagawa, K. 2012. Why are rewardless flowers divers? A simulation study. The 97th Annual Meeting of Ecological Society of America, PS102-168, Portland, Oregon, US.

Presentations without review

Kagawa, K., Takimoto, G. 2010. Is asymmetric structured food web stable for evolutionary changes? (in Japanese). The 57th Annual Meeting of Ecological Society of Japan, P2-077, Tokyo, Japan.

Kagawa, K., Takimoto, G. 2011. A possibility of sympatric speciation via pollination interaction (in Japanese). The 58th Annual Meeting of Ecological Society of Japan, P2-291, Hokkaido, Japan.

Kotaro, K. , Takimoto, G. 2012. Why rewardless flowers are diverse? The 5th East Asian Federation of Ecological Societies, P2-140A, Shiga, Japan.

Kagawa, K. 2012. Why and how color polymorphism in rewardless flowers evolved? ~A simulation study~ (in Japanese). The 28th Annual Meeting of Society of Population Ecology, S4-3, Funabashi, Chiba, Japan.

Kagawa, K. , Takimoto, G.2014. What kind of lineages will undergo adaptive radiation? ~Evolutionary roles of hybridization and sexual selection~ (in Japanese). The 61th Annual Meeting of Ecological Society of Japan, PA2-010, Hiroshima, Japan.

Kagawa, K. , Takimoto, G.2015. Roles of hybridization and magic traits in adaptive radiations. The 62th Annual Meeting of Ecological Society of Japan, I1-25, Kagoshima, Japan.


  • KOTARO Kagawa
    School of Statistical Thinking, The Institute of Statistical Mathematics, 10-3 Midori-cho, Tachikawa, Tokyo 190-8562, Japan

  • Email: kagawakoutarou(at mark)gmail.com