Spatial and Temporal Aspects of Occurrence ofMogeraSpecies in the Japanese Islands Inferred from Mitochondrial and Nuclear Gene Sequences

We assessed dispersal and vicariant events in four species of Japanese moles in the genera Mogera and Euroscaptor to better understand the factors shaping intra- and interspecific differentiation in Japanese moles. We used the combined viewpoints of molecular phylogeny and historical geology using nucleotide sequences of mitochondrial (cytochrome b; Cytb) and nuclear (A2ab, Bmp4, Tcf25, vWf) genes. The divergence times estimated from the molecular data were verified with available geological data on the chronology of fluctuations in sea level in the Korea Strait, assuming sequential migration and speciation events. This produced possible migration times of 5.6, 3.5, 2.4, and 1.3 million years ago for four species of Japanese moles, Euroscaptor mizura, Mogera tokudae, M. imaizumii, and M. wogura, respectively. For the western Japanese mole M. wogura, Cytb sequences revealed four major phylogroups with strong geographic affinities in southwestern Central Honshu (I), western Honshu/Shikoku (II), Kyushu/westernmost Honshu (III), and Korea/Russian Primorye (IV). The nuclear gene sequences supported the distinctiveness of phylogroups I and IV, indicating long, independent evolutionary histories. In contrast, phylogroups II and III were merged into a single geographic group based on the nuclear gene data. Intraspecific divergences in M. imaizumii and M. tokudae were rather apparent in Cytb but not in nuclear gene sequences. The results suggest that repeated dispersal events have occurred between the Asian continent and the Japanese Islands, and intensive vicariant events associated with abiotic and biotic factors have created higher levels of species and genetic diversities in moles occurring on the Japanese Islands.