Did cryptic refugia for beech trees exist in northern Japan during the last glacial period?

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K06152
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 40010:Forest science-related
• Research Institution: Forest Research and Management Organization
• Principal Investigator: Kitamura Keiko 国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員 等 (00343814)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 分布変遷

Outline of Final Research Achievements

We clarified the genetic diversity of relict beech populations and estimated the history of population dynamics. Beech leaves were collected from beech populations in Okushiri Island, an isolated island at the northern limit of beech populations, Hokkaido, and the Tohoku region, and a large-scale population genetic analysis was conducted using two genetic variation information of maternally inherited chloroplast DNA and bisexually inherited nuclear DNA. The results showed that the formation of the early beech population on Okushiri Island likely dates back to before the last glacial maximum (approximately 20,000 years ago), suggesting that Okushiri Island was a refugeum. In addition, an analysis of the phylogenetic relationships of beech forests located on both sides of the Tsugaru Strait indicated the possibility that refugea existed on the Matsumae Peninsula.

Free Research Field

個体群統計遺伝学

Academic Significance and Societal Importance of the Research Achievements

北半球における温帯林は約2万年前の最終氷期最盛期に南方に分布域を後退させていたものが、その後の気温上昇に伴って北に分布を拡大してきたと考えられてきた。しかし、最近のDNA解析技術とコンピューター解析手法の発展によって、温帯林の植物がこれまで考えられてきたよりも北方で最終氷期に生き延びていたことが明らかになり、氷期の厳しい環境下で生物が逃げ込んで生存していた逃避地（レフュージア）が次々と発見されつつある。一方、日本列島では北海道と日本アルプスの一部を除いて、氷河に覆われていなかったため、各地にレフュージアがあった可能性が高いと考えられる。本研究では温帯林の潜在逃避地が複数箇所示すことに成功した。