Study on the origin and developing process of genetic diversity in brown bear populations of Hokkaido and areas around the Okhotsk Sea

本项目的目的是调查北海道和鄂霍次克海周边地区棕熊种群的分子系统地理，并讨论它们的遗传多样性的起源和发展过程。1)基于线粒体DNA(MtDNA)分子系统学的北海道棕熊的三重种群结构是北海道特有的，在鄂霍次克海域没有发现类似的种群格局。2)对北海道列本岛Kafukai A遗址的棕熊骨骼进行了古代mtDNA分析，该遗址是鄂霍次克海沿岸5-12世纪发展起来的鄂霍次克文化遗址之一。将古代DNA数据与现存北海道棕熊的DNA数据进行了比较：分别出现在北海道中北部、东部和南部的三个mtDNA谱系，Kafukai A遗址的古代DNA被归类为北海道中北部或南部的血统。北海道南部的血统是在秋季死亡的幼年古熊身上发现的，而北海道中北部的血统是从春季死亡的成年北海道血统中发现的。这一结果表明，幼熊来自北海道南部，那里是鄂霍次克文化的外围地区，属于与本州东北地区有密切关系的外珠门或萨通文化。此外，鄂霍次克人已经建立了使用饲养熊的送熊仪式。3)北海道东部遗址的古代DNA数据显示，古代北海道棕熊的多态性高于现在的熊。4)大石岛的两块古代熊骨具有不同类型的北海道南部mtDNA谱系，表明它们来自不同的个体，通过人类活动从北海道南部传入。

The objective of this project was to investigate molecular phylogeography of brown bear populations in Hokkaido and areas around the Okhotsk Sea, and to discuss the origin and developing process of their genetic diversity. The results obtained in this study are as follows:1) The triple population structure of the Hokkaido brown bears, based on molecular phylogeny of mitochondrial DNA (mtDNA), is specific to Hokkaido, and no similar population patterns were found around the Okhotsk Sea areas.2) Ancient mtDNA analyses were made on brown bear bones from the Kafukai A site on Rebun Island of Hokkaido, which is one of Okhotsk Cultural sites developing along coastal regions of the Okhotsk Sea during 5-12 centuries, A.D. Compared the ancient DNA data with modern DNA data of extant brown bears of Hokkaido: three mtDNA lineages occurring separately in north-central, eastern, and southern Hokkaido, ancient DNAs of the Kafukai A site were classified into the north-central or southern Hokkaido lineage. The southern Hokkaido lineage was found in juvenile ancient bears which died in autumn, while the north-central Hokkaido lineage was identified from adults which died in spring. This result indicates that juvenile bears were brought from southern Hokkaido, which was an outside area of the Okhotsk culture and which belonged to the Epi-Jomon or Satsumon culture with a close relation to the Tohoku district of Honshu. In addition, the bear-sending ceremony using kept bears had already been established by the Okhotsk people.3) Ancient DNA data of eastern Hokkaido sites show higher polymorphisms in ancient Hokkaido brown bears than the present bears.4) Two ancient bear bones of Okushiri Island possessed different types of the southern Hokkaido mtDNA lineage, indicating they were from different individuals and brought from southern Hokkaido via human activity.