Abstract
We examined the morphological variation in twenty-five populations of Japanese white-toothed shrews (Crocidura dsinezumi); these were from islands of the Inland Sea (Setouchi), the Osumi, Tokara, Koshikijima, and Goto island chains of Kyushu, the Oki islands of Shimane, Sakushima of Aichi, and the Izu islands of Tokyo. Multivariate analysis (PCA, CDA) was conducted on mandible measurements. The overall size of the mandible (PC1) was not correlated with either island area or latitude, but the shape (height to length; PC2) correlated positively with latitude, suggesting that environmental factors such as temperature affected the shape. These five regions (the Inland Sea, the Osumi/Tokara, Koshikijima, and Izu islands chains, and the Oki islands) each have a different history. Nevertheless, morphological distance between island populations did not differ significantly among the above regions. This suggests that some island populations differentiated by chance in a short period of time. Populations on the Izu islands have a morphologically close relationship to that of mainland Kyushu. Shrews on the Izu islands might have been inadvertently introduced by man from Kyushu.
