Mitochondrial DNA polymorphism in subspecies of the Japanese Sika deer, Cervus nippon

Variations in the mitochondrial DNA (mtDNA) of Sika deer (Cervus nippon) from seven localities in Japan were examined to assess the degree of genetic differentiation among subspecies. The entire mtDNA of C. n. centralis, which is about 16,600 base pairs in length, was cloned into plasmids. Using various clones as hybridization probes, we constructed restriction maps of mtDNA for 59 deer and identified six different mtDNA genotypes. The genotypes observed in the subspecies centralis from Honshu Island (the mainland) were distinct from that of the same subspecies from the Tsushima Islands. By contrast, the subspecies yesoensis, which is distributed on Hokkaido Island, shared at least two mtDNA genotypes with the mainland centralis. Analysis of genetic distances showed that Sika deer on the Japanese islands consist of two distinct clusters, namely, the Hokkaido-Honshu (yesoensis-mainland centralis) and the Yakushima-Tsushima (yakushimae-Tsushima centralis) populations. The molecular phylogenetic data obtained for these subspecies do not reflect the present taxonomic status of these subspecies that is based on comparative morphometry. Genetic differentiation of Sika deer in the Japanese islands is a possible example of vicariance.