Kyushu University Academic Staff Educational and Research Activities Database
Researcher information (To researchers) Need Help? How to update
Kei Matsubayashi Last modified date:2022.06.19

E-Mail *Since the e-mail address is not displayed in Internet Explorer, please use another web browser:Google Chrome, safari.
 Reseacher Profiling Tool Kyushu University Pure
Academic Degree
Doctor of Philosophy
Country of degree conferring institution (Overseas)
Field of Specialization
Evolutionary Biology
ORCID(Open Researcher and Contributor ID)
Total Priod of education and research career in the foreign country
Research Interests
  • Genetic and ecological mechanisms of species diversification caused by adaptive population divergence
    keyword : adaptation, evolution, ecological genetics, speciation
Current and Past Project
  • Two closely related flightless species of Japanese beach weevil could demonstrate character displacement both the shape of male copulatory internal sacrum and the elytra coloration. In the project, the first goal is to figure out the condition of character displacement in multiple ecological traits. Further, I aim to test 'cascade reinforcement', which is indirect evolution of reproductive isolation between geographically distant populations of a species by character displacement with other species.
Academic Activities
1. @Matsubayashi, K. W., Yamaguchi, R, The speciation view: Disentangling multiple causes of adaptive and non‐adaptive radiation in terms of speciation., Population Ecology,, 64, 2, 95-107, 2022.01.
2. Kei Matsubayashi, Tetsuo I. Kohyama, Norio Kobayashi, Satoko Yamasaki, Masakazu Kuwajima, Haruo Katakura, Genetic divergence with ongoing gene flow is maintained by the use of different hosts in phytophagous ladybird beetles genus Henosepilachna, Journal of Evolutionary Biology, 10.1111/jeb.13071, 2017.04, 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 flow and heterogeneous genomic divergence in three closely related Japanese phytophagous ladybird beetles: Henosepilachna pustulosa, H. niponica and H. yasutomii. These species act as a generalist, a wild thistle (Cirsium spp.) specialist and a blue cohosh (Caulophyllum robustum) specialist, respectively, and their ranges differ accordingly. The two specialist species widely co-occur but are reproductively isolated solely due to their high specialisation to a particular host plant. Genome-wide amplified fragment-length polymorphism (AFLP) markers and mitochondrial cytochrome c oxidase subunit I (COI) gene sequences demonstrated obvious genome-wide divergence associated with both geographic distance and ecological divergence. However, a hybridisation assessment for both AFLP loci and the mitochondrial sequences revealed a certain degree of unidirectional gene flow between the two sympatric specialist species. Principal coordinates analysis (PCoA) based on all of the variable AFLP loci demonstrated that there are genetic similarities between populations from adjacent localities irrespective of the species (i.e. host range). However, a further comparative genome scan identified a few fractions of loci representing approximately 1 % of all loci as different-host associated outliers. These results suggest that these three species had a complex origin, which could be obscured by current gene flow, and that ecological divergence can be maintained with only a small fraction of the genome is related to different host use even when there is a certain degree of gene flow between sympatric species pairs..
3. Kei Matsubayashi, Sih Kahono, Sri Hartini, Naoyuki Fujiyama, Haruo Katakura, Redescription of the phytophagous ladybird beetle Henosepilachna diekei and descriptions of the related species from Indonesia, Insecta Matsumurana, 72, 1-16, 2016.09, The phytophagous ladybird beetle Henosepilachna diekei Jadwiszczak & Węgrzynowicz was redescribed on the basis of specimens from Indonesia and other south and southeastern Asian countries, and two new species related to it were described as H. nakanoi Matsubayashi & Katakura sp. nov. and H. uenoi Matsubayashi & Katakura sp. nov. Henosepilachna nakanoi is easily discernible from congeners by the unique structure of male and female genitalia. Henosepilachna uenoi has genitalia being nearly identical with H. diekei, but the two species sympatric in Bali are separable by the habitus shape, elytral maculation pattern, and host plants. A phylogenetic analysis based on mitochondrial NADH dehydrogenase subunit 2 (ND2) gene sequences also indicated that H. uenoi and H. diekei are genetically distinct, though very close to each other..
4. Kei Matsubayashi, Sih Kahono, Naoyuki Fujiyama, Jun Yokoyama, Department of Biology, Faculty of Science, Yamagata University, Suranga Basnagala, Yaowaluk Monthum, Rosli Hashim, Haruo Katakura, Geographic distribution, host plants, and morphological variation of the currently radiating phytophagous ladybird beetle Henosepilachna diekei, Journal of Natural History, 10.1080/00222933.2015.1079339, 50, 5-6, 363-376, 2015.09, To overview the morphological and ecological diversification within a species of phytophagous ladybird beetle Henosepilachna diekei, information concerning its distribution and host plant use was studied. This species was found widely in Southeast and South Asia from the Philippines through the Greater Sunda islands, a western part of Lesser Sundas, the Malay Peninsula to Sri Lanka. Mikania species (Asteraceae), M. micrantha in particular, were the most frequently utilized host plants, but some other plants belonging to Lamiaceae or Acanthaceae were also utilized by some local populations. Each population is possibly monophagous. According to morphological analyses, seven populations from four host plants at six sites on four Indonesian islands were grouped into two, one occurring on Java and Kalimantan (Borneo) and another on Sulawesi and Lombok, indicating that they were separated by the Wallace’s line. This morphological distinction was not correlated with the host plant use..
1. Kei Matsubayashi, Adaptive radiation and evolution of isolation barriers caused by specialization to different host plants in a phytophagous ladybird beetle, 個体群生態学会, 2017.10, [URL], Adaptive radiation is rapid diversification in a lineage correlating to ecological divergences. Nonetheless of the impact on biodiversity, the ecological and genetic mechanism of such rapid diversification remains unclear. To elucidate evolutionary causes of adaptive radiation, we detected the isolating barriers involved in the earliest stage of adaptive radiation of a phytophagous ladybird beetle, Henosepilachna diekei. Beetle populations collected from 4 host plant species showed highly specialized food acceptance and survivorship on the original host plant irrespective to the phylogenetic relationships. As these populations exhibited relatively weak isolating barrier other than host plant uses, we suggest that divergent host adaptation directly causes adaptive radiation in the species..
Membership in Academic Society
  • The Ecological Society Japan
  • Society of Evolutionary Studies, Japan
  • The Entomological Society of Japan
Educational Activities
I engage to basic higher education for 1st grade of students with having lecture in the practical causes of experiment of natural science, and Kikan education seminar.