Inttra-and interspecific genetic exchanges in Japanese small mammals through the Quaternary environmental fluctuations

日本小型哺乳动物的区系被认为是复杂的，因为在过去的几百万年里，可能发生了频繁的迁徙事件，从三条不同的路线穿过库页岛、朝鲜半岛和台湾。这些动物群也很复杂，因为日本从南到北的方向很长，可能有很多地理边界。为了了解日本小型啮齿动物的组织结构，我们利用线粒体细胞色素b和核IRBP基因的核苷酸序列，研究了来自北海道、本州-四国九州和琉球群岛三个地理区域的日本小型哺乳动物，如睡鼠、小鼠和田鼠的种内和种间遗传变异，并将它们与亚洲大陆采集的物种进行了比较，遗传差异表明日本小型啮齿动物具有较高的物种独特性，特别是在本州和琉球区域。同一地理区域的不同物种的遗传变异水平不同：然而，这意味着一个复杂的进化历史，这是物种特有的。日本粘虫、安氏真姬鼠、大姬鼠地理种群具有较高的遗传多样性水平。和Tokudaia osimens，以及日本种群和大陆种群之间的差异。这些数据表明，日本岛屿在提高东亚的遗传和物种多样性水平方面发挥了重要作用。此外，考虑到分子系统发育和分布模式，在许多小型哺乳动物物种形成过程中，可能发生了频繁的种间和种群间遗传交流。

The fauna of Japanese small mammals is thought to be complex because frequent migration events might have occurred during the last several million years from three different routes through Sakhalin, the Korean Peninsula, and Taiwan. The fauna is also complex because Japan is long in a south to north direction and potentially has many geographic borders. To understand the organization of Japanese small rodents, we examined intra- and interspecific genetic variation in Japanese small mammals, such as dormice, murine and voles, from three geographic domains of Hokkaido, Honshu-Shikoku-Kyushu and Ryukyu Islands, using nucleotide sequences for the mitochondrial cytochrome b and nuclear IRBP genes and compared them with those of species collected from the Asian continent, Genetic divergence indicated that Japanese small rodents possess relatively high species endemism, especially in the Honshu and Ryukyu domains. Levels of genetic variation differ among species from the same geographic domains : however, suggesting a complex evolutionary history that is species-specific. High levels of genetic diversity were observed among geographic populations of Glirulus japonicus, Eothenomys andersoni, Apodemus speciosus. and Tokudaia osimensis as well as between Japanese and continental populations of Clethrionomys rufocanus and C.rutilus. These data imply that the Japanese islands had played and important roll in increasing the levels of genetic and species diversity in East Asia. Moreover, considering the molecular phylogenies and distribution patterns, it is probable that frequent interspecific and interpopulational genetic exchanges have taken place during the course of speciation in many small mammalian species.