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Mammal Study
Abstract
Abstract.
The Japanese white-toothed shrew (Crocidura dsinezumi) is a species endemic to Japan. For this species, only minimal phylogeographic investigations have been conducted. We obtained DNA sequences of mitochondrial cytochrome b and control region and nuclear ApoB genes for 191 individuals of C. dsinezumi from 107 locations collected throughout its known range. In the phylogenetic trees based on mitochondrial DNA sequences, two haplogroups (Eastern and Western Clades) were recognized, and the demarcation line between them was located in central Honshu without an overlapping area. The estimated divergence time between the two major clades indicated that they could have diverged prior to the final geologic division of Hondo and the Asian Continent (100–150 KYA). For the ApoB gene, Types A, G, and R (heterozygote) were recognized although there was a single site mutation. Type A mainly occurs in eastern and central Japan and Types G and R in central and western Japan. It was suggested in the present study that some shrews in Hokkaido were introduced recently from eastern Honshu (possibly the Tohoku Region) whereas others might have been distributed there naturally, and that population in Jeju (South Korea) was introduced recently from Kyushu.
Some of the samples of shrews examined were provided by Fukui City Museum of Natural History (Yukako Naitoh), Osaka Museum of Natural History (Makiko Nishizawa and Takeshi Wada), Taga Town Museum (Yuji Abe and Shigefumi Kanao), Tottori Prefectural Museum (Kei Ichisawa), Sang-Hoon Han, Keiichi Kajiura, Zenkichi Shimizu, Yukako Naitoh, Hisashi Abe, Hiroaki Kariwa, Akio Shinohara, Jun J. Sato, Koichi Takeno, Kaito Okabe, Yoshihiro Matsuura, Kazuhiro Nishii, and Masashi Harada. Tomoyuki Namba and Yukako Naitoh helped with field work. Hitoshi Suzuki, Wataru Ohnishi, Tomohiro Nakayama, and Kazuhiro Koyasu assisted in collecting preserved samples. Masaru Kato collected detailed information for several samples. Also, Akira Sano, Makoto Asano, Masatsugu Suzuki, Shirow Tatsuzawa provided us with information about museums and private collections in which C. dsinezumi is preserved. Masatoshi Yasuda and Hidetoshi Ota provided us with information on the geological and biogeographical history of the southern islands of Japan. Karli Lawson-Shimizu proofed the English for an earlier version of the manuscript. Leslie Carraway also reviewed an earlier version of the manuscript. We express our deep gratitude to them. Author contributions were as follows: S.D.O. led the study and conducted field and laboratory work; K.Y. performed the phylogenetic analyses; Y.T., M.M. and M.A.I. collected shrew samples; S.A. conducted field and laboratory work. G.K. performed the estimation of divergence time between the shrew clades and population genetic analyses, and the seven authors above profoundly contributed to the present study though discussion; J.M., Y.U., E.S., T.T., and HSO conducted material collection.
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