Evolution of social structure and mating systems in a tribe Lamprologini cichlids: A model system of social evolution in vertebrate

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H03306
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 45040:Ecology and environment-related
• Research Institution: Osaka City University
• Principal Investigator: Kohda Masanori 大阪市立大学, 大学院理学研究科, 教授 (70192052)
• Co-Investigator(Kenkyū-buntansha): 太田 和孝 大阪市立大学, 大学院理学研究科, 博士奨励研究員 (50527900) ; 安房田 智司 大阪市立大学, 大学院理学研究科, 准教授 (60569002) ; 高橋 鉄美 兵庫県立大学, 自然・環境科学研究所, 教授 (70432359)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 古典的一妻多夫 / 雌優位社会 / 繁殖成功 / 性役割の逆転 / 雌の雄操作 / 古典的動物行動学 / 認知行動学 / 動物社会学

Outline of Final Research Achievements

Classical polyandry that shows the reversal of sex role has been documented in some birds, wherein typically large dominant females enjoy high reproductive success than males. We investigated this type of mating system in cichlid fish Julidochromis marlieri in their habitats in Lake Tanganyika. Large females had large territories which rarely overlapped each other, and enclosed 1-3 nests with attending males. Females spawned eggs into several nests at which egg clutches were fertilized by the respective males. This breeding system are classical polyandry. The sex role of this fish is reversed, namely female-female fight is more frequent and severe than male-male fight, males took parental care more. This classical polyandry is similar to that of birds. This will be the first document of fish classical polyandry in the world.

Free Research Field

行動生態学

Academic Significance and Societal Importance of the Research Achievements

我々は、魚類での古典的一妻多夫の実態が世界で初めて明らかにすることができた。男性優位社会のヒトによって、魚類にさえこのような「女性優位社会」が存在する自身がヒト社会に与える影響は大きいと考える。もちろん、この発見は従来鳥類で考えられてきた仮説を全く異なる分類群の動物で検証したことの意義は大きい。
また、寒冷地群集と熱帯群集における動物の認知能力の進化に関する一般則に対する仮説を提唱できたことも大きい。