title: Phylogeographic and Demographic Analysis of the Asian Black Bear (Ursus thibetanus) Based on Mitochondrial DNA.
abstract: The Asian black bear Ursus thibetanus is widely distributed in Asia and is adapted to broad-leaved deciduous forests, playing an important ecological role in the natural environment. Several subspecies of U. thibetanus have been recognized, one of which, the Japanese black bear, is distributed in the Japanese archipelago. Recent molecular phylogeographic studies clarified that this subspecies is genetically distantly related to continental subspecies, suggesting an earlier origin. However, the evolutionary relationship between the Japanese and continental subspecies remained unclear. To understand the evolution of the Asian black bear in relation to geological events such as climatic and transgression-regression cycles, a reliable time estimation is also essential. To address these issues, we determined and analyzed the mt-genome of the Japanese subspecies. This indicates that the Japanese subspecies initially diverged from other Asian black bears in around 1.46Ma. The Northern continental population (northeast China, Russia, Korean peninsula) subsequently evolved, relatively recently, from the Southern continental population (southern China and Southeast Asia). While the Japanese black bear has an early origin, the tMRCAs and the dynamics of population sizes suggest that it dispersed relatively recently in the main Japanese islands: during the late Middle and Late Pleistocene, probably during or soon after the extinction of the brown bear in Honshu in the same period. Our estimation that the population size of the Japanese subspecies increased rapidly during the Late Pleistocene is the first evidential signal of a niche exchange between brown bears and black bears in the Japanese main islands. This interpretation seems plausible but was not corroborated by paleontological evidence that fossil record of the Japanese subspecies limited after the Late Pleistocene. We also report here a new fossil record of the oldest Japanese black bear from the Middle Pleistocene, and it supports our new evolutionary hypothesis of the Japanese black bear.
authors.affiliation: School of Life Sciences, Fudan University, SongHu Rd. 2005, Shanghai, 200438, China.
authors.forename: Jiaqi
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Geology and Paleontology, National Museum of Nature and Science, Amakubo 4-1-1, Tsukuba, Ibaraki, 305-0005, Japan; Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki, 305-8572, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Kohno
authors.affiliation: The Institute of Statistical Mathematics, Midori-cho 10-3, Tachikawa, Tokyo, 190-8562, Japan.
authors.forename: Shuhei
authors.initials: S
authors.lastname: Mano
authors.affiliation: Hiroshima City Asa Zoological Park, Asakita-ku, Hiroshima city, Hiroshima, 731-3355, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Fukumoto
authors.affiliation: School of Advanced Sciences, The Graduate University for Advanced Studies, Shonan Village, Hayama, Kanagawa, 240-0193, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Tanabe
authors.affiliation: School of Life Sciences, Fudan University, SongHu Rd. 2005, Shanghai, 200438, China; The Institute of Statistical Mathematics, Midori-cho 10-3, Tachikawa, Tokyo, 190-8562, Japan.
authors.forename: Masami
authors.initials: M
authors.lastname: Hasegawa
authors.affiliation: School of Life Sciences, Fudan University, SongHu Rd. 2005, Shanghai, 200438, China; The Institute of Statistical Mathematics, Midori-cho 10-3, Tachikawa, Tokyo, 190-8562, Japan; School of Advanced Sciences, The Graduate University for Advanced Studies, Shonan Village, Hayama, Kanagawa, 240-0193, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yonezawa
mesh_terms: D000818:Animals; D001208:Asia; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D008297:Male; D010802:Phylogeny; D058974:Phylogeography; D001503:Ursidae / Q000235:genetics*
chemical_list: D004272:DNA, Mitochondrial