Did the reverse colonization of plants based on multiple collisions of the proto-Izu Islands produce a biodiversity hotspot region in Japan?

2018 Fiscal Year Final Research Report

• Project/Area Number: 15K07473
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Forest science
• Research Institution: Niigata University
• Principal Investigator: ABE Harue 新潟大学, 自然科学系, 准教授 (60462272)
• Co-Investigator(Kenkyū-buntansha): 陶山 佳久 東北大学, 農学研究科, 准教授 (60282315)
• Research Collaborator: WATANABE Yoichi
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: フォッサマグナ要素 / 再移入 / ヒサカキ / ツバキ / コメツツジ

Outline of Final Research Achievements

Repeated collisions between oceanic islands and mainland Japan, through movement of tectonic plates, have generated a biodiversity hotspot in Japan. As the plate continued to move, these islands collided with the main Japanese islands. This proposes a biogeographic scenario that, in the past, mainland species colonized newly forming volcanic islands and then underwent independent processes of community assembly, adaptive evolution, and speciation. When this volcanic arc collided with the mainland, these island-adapted species came into contact with their mainland evolutionary cousins.
We reported a review of the published population phylogenies of plant taxa. We formulate the hypothesis that the pattern of repeated secondary contact of mainland and island sister species, and their subsequent interactions, have generated a biodiversity hotspot in Japan.

Free Research Field

島嶼生物学

Academic Significance and Societal Importance of the Research Achievements

日本における重要な植生区分である①フォッサマグナ要素の成立に至る要因を、プレート移動に基づく島からの再移入という新しい着想に基づき評価を行う点が独創性である。研究方法は、②大量遺伝子データを用いることで、島からの再移入の効果を詳細に評価できること、③形態系統樹、種系統樹、機能遺伝子に基づく系統樹を比較することにより、島嶼で獲得した機能の保存・消失を形態学的、遺伝学的両方の側面から評価できることが特色である。本研究は、島嶼の生物群集が大陸の生物群集に付加される過程でおこる植物の適応進化を明らかにし、群集構成種の適応進化が群集の動態へフィードバックされる過程の実証研究に繋がる研究である。