Professor Chen Yihui and Associate Professor Wu Qixun of the Department of Life Sciences of the Bunka University formed a research team with the University of the Ryukyus, Kyoto University, and the National Museum of Science of Japan. Starting from the genetic study of Ehrlich's tree frog populations, they used whole-genome analysis to compare the populations of Taiwan, Ishigaki Island, and Iriomote Island. The research showed that even though sea levels dropped during the Ice Age and the islands may have been in contact through land bridges, the populations still retained their respective genetic characteristics. The results provide an important research basis for further understanding the evolution and group differentiation of diverse species on islands, and were recently published in the international journal "Zoological Studies".
This study lasted nearly 4 years from the initial discussion to the publication of the results. The research team combined field surveys and genetic analysis in Taiwan and Japan and found that the Ishigaki Island, Iriomote Island, northern Taiwan, and central Taiwan populations each formed major genetic groups, indicating that the same species has accumulated its own genetic characteristics after long-term evolution on different islands. The research results also provide new research information for understanding how island organisms are affected by geographical isolation, environmental conditions and their own ecological characteristics to form different genetic characteristics.
Among them, the Ishigaki Island and Iriomote Island groups had differentiated early in their evolution. Research speculates that during the Pleistocene glacial period when sea levels dropped, the two islands may have come into contact again through land bridges, and a small amount of genetic exchange occurred between the groups, but the genetic differences did not disappear. Research results show that in addition to geographical isolation, the ethnic differentiation of island organisms is affected by the habitat environment and the ecological characteristics of the species themselves, which may also affect the genetic exchange between different ethnic groups.
Chen Yihui and Wu Qixun pointed out that although the Ehrlich's tree frogs in Taiwan and Japan's Ryukyu Islands belong to the same species, the evolution of the populations in different regions can be seen from the whole genome data. Compared with observing group relationships only from geographical distribution or partial genes, this time more complete genomic data allows the research team to further understand the genetic structure and evolutionary relationships of different island groups. In the future, the research team will further explore the population evolution and genetic differentiation of amphibians, reptiles and other island organisms, and compare different species to understand how the island environment and biological characteristics jointly affect the evolution of the population.
This research is also an extension of the long-term academic cooperation between the Department of Life Sciences at the University of Liberal Arts and the University of the Ryukyus in Japan. The two parties have been promoting international joint courses in biology since 2013, arranging for Japanese teachers and students to come to Taiwan to teach, and also leading students to the University of the Ryukyus for ex-situ study. In 2018, they signed a sister school cooperation. During the course of this study, a Japanese research team came to Taiwan to conduct field sampling of Ehrlich's tree frogs, while a Chinese Culture University research team went to Japan to participate in follow-up research and analysis, gradually completing the research from field investigation, sample collection to genetic data analysis.
