Morphological differentiation of island populations of Japanese white-toothed shrews, Crocidura dsinezumi

Abstract

Morphological variation was examined in seven populations of Japanese white-toothed shrews, Crocidura dsinezumi, from three islands of Izu (Toshima, Niijima, Shikinejima), Sakushima island, Aichi (Nagoya and Kasugai), and two islands of Oki (Dogo and Nishinoshima). Uni- and multi-variate analyses (PCA, CDA) were conducted on the basis of mandible measurements. The shrews of Shikinejima showed no significant divergence from those of Niijima, and they formed a cluster with those of Toshima. The shrews of Sakushima, Aichi, and two islands of Oki formed another cluster, as differences between those from Sakushima and Aichi were small. Morphological divergence in shrews was very small within the Izu Islands, between Sakushima and Aichi, or between the islands of Oki, in contrast to house mice (Mus musculus) from the Izu Islands and Sakushima (Takada et al., 1994, 1999). The shrews on the Izu Islands and Sakushima seem to have been introduced by humans.