Ancient DNA reveals multiple origins and migration waves of extinct Japanese brown bear lineages

• Published in: Royal Society Open Science
• Main Authors: Takahiro Segawa, Takahiro Yonezawa, Hiroshi Mori, Ayumi Akiyoshi, Morten E. Allentoft, Ayako Kohno, Fuyuki Tokanai, Eske Willerslev, Naoki Kohno, Hidenori Nishihara
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 2021
• Subjects: ancient DNA; brown bear; mitochondrial genomes; Pleistocene megafauna; Science; Q; Ursus arctos
• Online Access: https://doi.org/10.1098/rsos.210518; https://doaj.org/article/7062162df43b4629b0553b32b34cb14c

Little is known about how mammalian biogeography on islands was affected by sea-level fluctuations. In the Japanese Archipelago, brown bears (Ursus arctos) currently inhabit only Hokkaido, the northern island, but Pleistocene fossils indicate a past distribution throughout Honshu, Japan's largest island. However, the difficulty of recovering ancient DNA from fossils in temperate East Asia has limited our understanding of their evolutionary history. Here, we analysed mitochondrial DNA from a 32 500-year-old brown bear fossil from Honshu. Our results show that this individual belonged to a previously unknown lineage that split approximately 160 Ka from its sister lineage, the southern Hokkaido clade. This divergence time and fossil record suggest that brown bears migrated from the Eurasian continent to Honshu at least twice; the first population was an early-diverging lineage (greater than 340 Ka), and the second migrated via Hokkaido after approximately 160 Ka, during the ice age. Thus, glacial-age sea-level falls might have facilitated migrations of large mammals more frequently than previously thought, which may have had a substantial impact on ecosystem dynamics in these isolated islands.