Intraspecific differentiation in the lesser Japanese mole in eastern Honshu, Japan, indicated by nuclear and mitochondrial gene analyses.

The lesser Japanese mole, Mogera imaizumii, recognized by Motokawa and Abe (1996), occurs in eastern Honshu, western Honshu and Shikoku. Mitochondrial and nuclear DNA were analyzed for mole samples from eastern Honshu to elucidate intraspecific differentiation. Analyses of sequences of the mitochondrial cytochrome b gene (Cytb) and of a restriction fragment length polymorphism of the nuclear 28S ribosomal RNA gene spacer (rDNA-RFLP) revealed two genetic types, partially corresponding to Hutterer's (1993) taxa, M. wogura (= M. imaizumii) and M. minor. Most samples showed either of two combinations of mitochondrial / nuclear gene types. However, two specimens showed a different combination. This incongruent combination of mitochondrial and nuclear genes might have derived, in part, from an introgression event between genetically differentiated populations after secondary contact during the evolutionary history of the lesser Japanese mole in eastern Honshu

Evidence of late root formation of molars in Anderson’s red-backed vole, Eothenomys andersoni (Thomas, 1905) (Cricetidae, Rodentia), and arguments for its generic allocation

We evaluated the molars in Anderson’s red-backed vole (n = 114) from the Kii Peninsula of Honshu, Japan. Two of the specimens are considered extremely old aged based on their dimensions and on the loss of alveolar capsules of M2, and a third one is also old based on its strongly worn left M3 and M1. Of the former two individuals, one showed an incipient closure of re-entrant angles at its basal end, as estimated from the difference between the occlusal patterns of the occlusal and basal surfaces of the left M2. The latter individual also showed a complete closure of the basal end in the left M3. These patterns differ from incipient roots observed in other vole taxa but were similar to a previous example of incipient roots in Anderson’s red-backed vole. Therefore, we suggest that molar roots in this species form at an extremely late age or by strong wear. Root formation in molars is considered an important diagnostic character, as Eothenomys molars lack roots, while Craseomys molars develop roots at a late age. However, this dental character may be particularly difficult to assess in voles under natural conditions. Considering previous phylogenetic findings based on molecular analyses, Craseomys is the most appropriate genus for Anderson’s and other Asiatic red-backed voles

Restriction fragment length polymorphism of nuclear rDNA in Sorex caecutiens/shinto group (Eulipotyphla, Soricidae)

We estimated phylogenetic relationships among shrews of the Sorex caecutiens/shinto group (Eulipotyphla, Soricidae) from various locations through its range, based on restriction fragment length polymorphism (RFLP) analysis of the nuclear ribosomal RNA gene (rDNA) spacer region. Seven rDNA-RFLP repetitive types (repetypes) were recognized among 15 shrews examined. Restriction patterns of Sorex caecutiens Laxmann, 1788 and S. shinto Thomas, 1905 were distinguishable from each other, but the separation was not statistically supported in the maximum parsimony analysis. The RFLP repetype from Cheju Island was close to that of S. caecutiens from the Eurasian continent, indicating that the shrew of Cheju should be classified as S. caecutiens. Within S. caecutiens, there were two alternative phylogenetic hypotheses. According to a parsimonious tree and a simple network, the Hokkaido population was regarded to be derived from the Sakhalin population, which in turn was derived from the continental population. Alternatively, it was inferred that the continent and Hokkaido populations were firstly separated from the ancestral population, and then shrews from both populations immigrated into Sakhalin and hybridization occurred there. The latter hypothesis seems to be more plausible because it is more congruent with a previous mitochondrial phylogeny