2021 Fiscal Year Final Research Report

Why can island adaptive radiations of birds occur? An approach using mathematical models and geometric morphometrics

Research Project

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Project/Area Number	18K06397
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Review Section	Basic Section 45030:Biodiversity and systematics-related
Research Institution	Yamashina Institute for Ornithology
Principal Investigator	Yamasaki Takeshi 公益財団法人山階鳥類研究所, 研究所, 研究員 (70390755)
Co-Investigator(Kenkyū-buntansha)	島田将喜帝京科学大学, 生命環境学部, 准教授 (10447922) 荻原直道東京大学, 大学院理学系研究科(理学部), 教授 (70324605) 小林豊高知工科大学, 経済・マネジメント学群, 教授 (70517169) 土岐田昌和東邦大学, 理学部, 准教授 (80422921)
Project Period (FY)	2018-04-01 – 2022-03-31
Keywords	適応放散 / 種分化 / 数理モデル / シミュレーション / 幾何学的形態測定学 / 鳥類
Outline of Final Research Achievements	In this study, we asked the following questions: "Why can adaptive radiations occur in birds on oceanic islands?" and "What is the difference between birds that do and do not undergo adaptive radiation on oceanic islands?" For the first question, it was a puzzle why ancestral species with high oversea dispersal ability would be genetically fragmented due to narrow straits within an archipelago. Our computer simulations revealed that under conditions in which adaptive radiation occurs, natural selection favors a rapid decrease in dispersal ability. Regarding the second question, there was a hypothesis that the evolvability of bill morphology, which plays an important role in the adaptation of birds to their environment, determines whether adaptive radiation occurs on oceanic islands. However, a 3D geometric morphometrics study on crows did not support this hypothesis.
Free Research Field	進化生物学
Academic Significance and Societal Importance of the Research Achievements	人類の活動により、生物多様性の急激な喪失が続いている現代において、生物多様性についての理解の深化は急務である。海洋島の鳥の適応放散は、生物多様性の創出メカニズムを解明するための理想的な材料とみなされてきた。それは著しく多様な種を含む一方、観察がきわめて容易という特性を持つためである（海洋島の生態系はシンプルであり、そこに住む鳥は人間に対する警戒心を欠く）。本研究は、このように重要な題材について、「高い海上分散力を持つはずの鳥類がなぜ海洋島において多数の種に分化することができるのか」という、長年の謎を解決できた。