Abstract
We examined morphological variation in twelve populations of the harvest mouse (Micromys minutus) on the Oki Islands, and from Honshu to Kyushu. Multivariate analyses (PCA, CDA) were conducted on the mandible dimensions. Significant differences among the populations were found for the second and the third principal component scores (PC2, PC3; shape factors), but not for the first principal component score (PC1; a size factor). PC2 sample means were significantly correlated with island area, and some environmental effects might therefore affect shape variation. A canonical discriminant analysis revealed morphological differences among islets from the Oki Islands. Genetic drift coupled with the geographical isolation seemed to lead to these differences. On the other hand, the populations did not show inter-regional morphological variation in mandible size, and did not differ morphologically among populations from far away localities. This may be accounted for by a low level of genetic diversity in the harvest mouse from the Japanese Archipelago, as was found by Yasuda et al. (2005).
