Dr. Tetsu Yatsuyanagi1, Dr. Takashi Kanbe1, Mr. Kazuya Fujii1, Mrs. Shouko Inoue1, Prof. Hitoshi Araki1
1Hokkaido University, Sapporo, Japan
Biography:
Hitoshi Araki is a professor of animal ecology in the Research Faculty of Agriculture at Hokkaido University in Japan. After obtaining his Ph.D. at Kyushu University in 2001, he worked for the University of Chicago and Oregon State University in the U.S. from 2001 to 2007 as a post-doctoral fellow. He then moved to the Swiss Federal Institute of Aquatic Science and Technology in Switzerland in 2008 as a group leader. He became a full professor at Hokkaido University in 2013. His research interests include molecular ecology, population genetics, and conservation biology.
Abstract:
Phylogeography bears an important part in ecology and evolution. However, current phylogeographic studies are largely constrained by limited numbers of individual samples. Using an environmental DNA (eDNA) assay for phylogeographic analyses, this study provides detailed information regarding the history of Siberian stone loach Barbatula toni, a primary freshwater fish across the whole range of Hokkaido, Japan. Based on an eDNA metabarcoding on 293 river water samples, we detected eDNA from B. toni in 189 rivers. A total of 51 samples, representing the entire island, were then selected from the B. toni eDNA-positive sample set for the subsequent analyses. To elucidate the phylogeographic structure of B. toni, newly developed eDNA metabarcoding primers (Barba-cytb-F/R) were applied to these samples, specifically targeting their haplotypic variation in cytochrome b. After a bioinformatic processing to mitigate haplotypic false positives, a total of 50 eDNA haplotypes were identified. Two regionally restricted, genetically distinct lineages of the species were revealed as a result of phylogeographic analyses on the haplotypes and tissue-derived DNA from B. toni. According to a molecular clock analysis, they have been genetically isolated for at least 1.5 million years, suggesting their ancient origin and colonization of Hokkaido, presumably in the glacial periods. These results demonstrate how freshwater fishes can alter their distributions over evolutionary timescales and how eDNA assay can deepen our understanding of phylogeography.