PHYLOGENETIC POSITION AND GEOGRAPHIC DIFFERENTIATION OF THE JAPANESE DORMOUSE, GLIRULUS-JAPONICUS, REVEALED BY VARIATIONS AMONG RDNA, MTDNAAND THE SRY GENE

The Japanese dormouse, Glirulus japonicus, is the only extant lineage that represents this genus and it has been classified as a single spec ies distributed on the three main islands of Japan, namely Honshu, Shi koku and Kyushu. However, individuals collected from Fukui, Wakayama a nd Kochi Prefectures (southwestern part of Japan) yielded distinctly d ifferent profiles of restriction fragments of the nuclear ribosomal DN A (rDNA) spacer from those collected from Yamanashi and Nagano Prefect ures (central Japan). The estimated sequence divergence between the tw o groups was 2.8% on average, which corresponds to a putative divergen ce some two million years ago. Representing mitochondrial DNA (mtDNA) sequences, 402 bases of cytochrome b gene were determined by direct se quencing and the estimated extent of the sequence divergence between t he two groups was 6.5-7%. Differences between the two geographic group s were also substantial in the sequences of about 300 base-fragments f rom the Y-linked, sex-determining locus, Sry. To assess the phylogenet ic relationships between the Japanese dormouse and members of the fami ly Myoxidae, we compared sequences of mitochondrial 12S rRNA gene of J apanese dormice with those of the forest dormouse (Dryomys nitedula) a nd the common dormouse (Muscardinus avellanarius), two continental gen era thought to be closely related to the genus Glirulus. The results s howed that the sequences from Japanese dormice were distinct from any sequences of the two continental species and the extent of the differe nces were somewhat similar to that between the rat (Rattus norvegicus) and the hamster (Mesocricetus auratus).