To investigate the phylogenetic relationships of brown bears (Ursus arctos) on Sakhalin Island in the Far East, mitochondrial DNA (mtDNA) sequences were analyzed for 27 ancient and five contemporary specimens of brown bears obtained from Sakhalin. We successfully determined partial sequences of the mtDNA control region (254–394 base-pairs) and identified six novel haplotypes. All sequences from bears on Sakhalin grouped phylogenetically with clade 3a but were not clearly distinguishable as to subclades 3a1 and 3a2. However, by application of APLP method for detecting single-nucleotide polymorphisms (SNPs) specific to clades, the samples from Sakhalin were all identified to clade 3a1, which is currently widespread in eastern continental Eurasia. Although the ancestors of brown bears on Hokkaido Island, Japan, migrated from continental Eurasia through Sakhalin, none of the clades previously found on Hokkaido (clades 3a2, 3b, and 4) were detected on Sakhalin. Our results suggest that an ancestral bear population from clade 3a1 migrated from continental Eurasia to Sakhalin, independently and after the migration of clade 3a2 to Hokkaido. Alternatively, clade 3a2 could have evolved from phylogenetically closely related clade 3a1 due to geographical isolation on Hokkaido. Our data confirm that bear skull remains from an Okhotsk Cultural archaeological site on small Rebun Island off the northwest coast of Hokkaido were transported from Hokkaido, rather than from Sakhalin.

调查棕熊的亲缘关系（棕熊）在远东的萨哈林岛上，分析了从萨哈林岛获得的27头古代和5头棕色熊的线粒体DNA（mtDNA）序列。我们成功地确定了mtDNA控制区的部分序列（254-394个碱基对），并确定了6种新颖的单倍型。来自萨哈林岛上熊的所有序列在进化上都与进化枝3a分组在一起，但对于子进化枝3a1和3a2却没有明显区别。然而，通过应用APLP方法检测进化枝特有的单核苷酸多态性（SNP），所有来自萨哈林岛的样品均被鉴定为进化枝3a1，目前在欧亚大陆东部普遍存在。尽管日本北海道岛上的棕熊的祖先从欧亚大陆迁移到萨哈林岛，但以前在北海道上没有发现任何进化枝（进化枝3a2，在萨哈林岛上发现了3b和4）。我们的结果表明，进化支3a1的祖先熊种群独立地以及在进化支3a2迁移到北海道后从欧亚大陆迁移到萨哈林岛。或者，由于北海道的地理隔离，进化枝3a2可能从系统发育上密切相关的进化枝3a1进化而来。我们的数据证实，来自北海道西北海岸小礼文岛上的鄂霍次克文化遗址的熊头骨遗骸是从北海道而非萨哈林岛运来的。由于北海道的地理隔离，进化枝3a2可能从系统发育密切相关的进化枝3a1进化而来。我们的数据证实，来自北海道西北海岸小礼文岛上的鄂霍次克文化遗址的熊头骨遗骸是从北海道而非萨哈林岛运来的。由于北海道的地理隔离，进化枝3a2可能从系统发育密切相关的进化枝3a1进化而来。我们的数据证实，来自北海道西北海岸小礼文岛上的鄂霍次克文化遗址的熊头骨遗骸是从北海道而非萨哈林岛运来的。