Kei Matsubayashi

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Ladybird beetles in the tribe Epilachnini include notorious crop pests and model species studied intensively in various fields of evolutionary biology. From a combined dataset of mitochondrial (ND2) and nuclear (28S) DNA sequences, we reconstructed the phylogeny of 46 species of Epilachnini from Asia, Africa, America, and the Australian region: 16 species(More)
Reproductive isolation between species may often be attained by multiple isolating barriers, but the components are rarely studied in animal taxa. To elucidate the nature of multiple isolating barriers, we quantified the strength of three premating barriers, including ecologically based ones (seasonal, habitat, and sexual), two postmating-prehatching(More)
Reinforcement learning is a technique to learn suitable action policies that maximize utility, via the clue of reinforcement signals: reward or punishment. Q-learning, a widely used reinforcement learning method, has been analyzed in much research on autonomous agents. However, as the size of the problem space increases , agents need more computational(More)
Detecting the isolating barrier that arises earliest in speciation is critically important to understanding the mechanism of species formation. We tested isolating barriers between host races of a phytophagous ladybird beetle, Henosepilachna diekei (Coleoptera: Coccinellidae: Epilachnine), that occur sympatrically on distinct host plants. We conducted field(More)
In multi-agent environments where agents independently generate and execute plans to satisfy their goals, the resulting plans may sometimes overlap. In this paper, we propose a collaboration mechanism using social law, through which rational agents can smoothly delegate and receive the execution of the overlapping parts of plans in order to reduce the cost(More)
Adaptation to different environments can promote population divergence via natural selection even in the presence of gene flow - a phenomenon that typically occurs during ecological speciation. To elucidate how natural selection promotes and maintains population divergence during speciation, we investigated the population genetic structure, degree of gene(More)
Acknowledgments This study has been completed with the benet of advice from many people during my Master and Ph.D. courses at Keio University. Here, I express my thanks to them for their ideas and suggestions. It is my great pleasure to thank Prof. Masakazu Nakanishi, my adviser, for his encouragement and for support throughout my undergraduate and graduate(More)
The ladybird beetles Propylea quatuordecimpunctata and P. japonica have largely overlapping distributions in northern Japan, and in the laboratory produce fertile hybrids. In this study, we surveyed the distribution and morphological differentiation of these species and the hybrids in natural populations, with a focus on western Hokkaido, northern Japan.(More)
x Abstract In Distributed Problem Solving (DPS), Dynamic Reorganization is said to be eective in order to cope with tradeos between the global accuracy and the e-ciency of the problem solving. In order to realize an architecture for the Dynamic Reorganization, it is important to consider a question \When should agents reorganize ? ". Such architectures,(More)
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