Phylogenetic Position and Geographic Differentiation of the Japanese Dormouse, Glirulus japonicus, Revealed by Variations among rDNA, mtDNA and the Sry Gene

Abstract The Japanese dormouse, Glirulus japonicus, is the only extant lineage that represents this genus and it has been classified as a single species distributed on the three main islands of Japan, namely Honshu, Shikoku and Kyushu. However, individuals collected from Fukui, Wakayama and Kochi Prefectures (southwestern part of Japan) yielded distinctly different profiles of restriction fragments of the nuclear ribosomal DNA (rDNA) spacer from those collected from Yamanashi and Nagano Prefectures (central Japan). The estimated sequence divergence between the two groups was 2.8% on average, which corresponds to a putative divergence some two million years ago. Representing mitochondrial DNA (mtDNA) sequences, 402 bases of cytochrome b gene were determined by direct sequencing and the estimated extent of the sequence divergence between the two groups was 6.5–7%. Differences between the two geographic groups were also substantial in the sequences of about 300 base-fragments from the Y-linked, sex-determini...