Molecular Phylogeographic Variation in the Siberian Weasel (Mustela sibirica) in Asia, Including Japan, Examined by ddRAD-Seq Analysis

The Siberian weasel (<i>Mustela sibirica</i>) is a mustelid widely distributed in Asia. Previous mitochondrial DNA (mtDNA) phylogenetic analyses showed that this species consists of two clades (the northern and southern lineages) in native populations, and that introduced populations currently expanding in western Japan could have originated from Korea. To elucidate the origin and history of expansion, genome-wide single nucleotide polymorphisms (SNPs) were obtained through double-digestion restriction site-associated DNA sequencing (ddRAD-seq) of biparentally inherited nuclear DNA in addition to the maternally inherited mtDNA. The SNPs were used to study the population genetics of Siberian weasels across the Asian continent, the Korean Peninsula, Taiwan, and the Japanese archipelago, including Tsushima and three of the four main islands: western part of Honshu, Shikoku, and Kyushu. Our results showed genetic differentiation among native populations between the continent and Taiwan. The Taiwan population differed markedly from other populations. Our phylogenetic analyses indicated that introduced founders from the continent and their offspring expanded their range from west to east in Japan, which is consistent with a previously reported mtDNA phylogeny. Our study detected no evidence of hybridization between the Siberian weasel and the related Japanese weasel (<i>M. itatsi</i>), which have overlapping habitat ranges.