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Phylogenetical positions of Sorex specimens unassigned to species from Cheju Island, Korea, and S. caecutiens from southern Korean Peninsula were investigated based on full nucleotide sequences (1,140 bp) of the mitochondrial cytochrome b gene, comparing specimens of the S. caecutiens/shinto group from locations throughout its range. In the phylogenetic tree obtained, S. caecutiens were separated into two main groups: Hokkaido and Continent-Sakhalin-Cheju clusters. Shrews from Cheju and Korean Peninsula were included in the latter cluster. Thus, we suggest that the shrew on Cheju Island should be ranked as S. caecutiens, although taxonomic description of the shrew has to be conducted elsewhere. The Cheju shrews formed a single sub-cluster while the peninsular shrews were not included in a single sub-cluster. The clustering of individuals in Continent-Sakhalin-Cheju cluster did not always reflect the geographical proximity of their capture locations. We interpret these findings as indicating ancestral isolation of a Hokkaido population and recent rapid range expansion of the modern population in Eurasian Continent-Sakhalin-Cheju.

Growth, metamorphosis, and gape-limited cannibalism and predation on tadpoles (Rana pirica) in larvae of salamanders (Hynobius retardatus) were investigated in laboratory. Larval period and the size at metamorphosis were correlated positively to one another in the salamanders. When embryos were exposed to low temperature, larval period were prolonged and the size at metamorphosis increased in the salamanders while larval period were extended and the size at metamorphosis decreased in the frogs. Salamander larvae reared in group had shorter larval period and smaller size at metamorphosis than those reared individually. Small salamander larvae were more vulnerable to cannibalism and mutilation than large ones. Tadpoles incurred high probability of predation and mutilation by salamander larvae even when the head widths of tadpoles attained the maximum sizes.