Phylogenetic relationships between the Ophidiasteridae and Goniasteridae (Asteroidea): Evolution and adaptation from the deep sea to the shallow waters

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K06327
• 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: National Museum of Nature and Science, Tokyo
• Principal Investigator: Fujita Toshihiko 独立行政法人国立科学博物館, 動物研究部, 部長 (70222263)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 分子系統解析 / ホウキボシ科 / ゴカクヒトデ科 / ヒトデ綱 / 深海 / 分類体系 / 多様化

Outline of Final Research Achievements

Phylogenetic studies on the morphological and molecular characteristics of the families Ophidiasteridae and Goniasteridae were conducted. Traditional systematics considered ophidiasterids, with slender arms, to be dominant in shallow seas, while goniasterids, with pentagonal bodies, were thought to be dominant in the deep sea. However, detailed molecular phylogenetic analysis revealed that many species previously classified under Ophidiasteridae actually belong to Goniasteridae, indicating a significant need to revise the classification system. It was found that goniasterids are widely distributed from the deep sea to shallow waters, and species inhabiting shallow seas have similar morphologies to sympatric ophidiasterids. Ancestral state reconstruction suggested an evolutionary trend opposite to what has been hypothesized for many benthic animals, revealing an expansion from deep to shallow seas and corresponding morphological adaptations to shallow water environments.

Free Research Field

動物系統分類学

Academic Significance and Societal Importance of the Research Achievements

生物は進化によって，様々な形態を生み出してきた．形態がそれぞれの系統でどのように変化したのかを追うことは，進化を理解する上での重要な課題である．ヒトデ類においては，これまで形態から推定されていた分類・系統が，分子系統解析によって大きく見直されつつある．系統に基づく分類体系と分類形質とを対比させた分析から，進化の実像がわかるようになり，浅海から浅海へ進出して多様化するという，これまであまり指摘されていなかった進化の道筋を示唆することができた．