2023 Fiscal Year Final Research Report

Phenotypic plasticity of life history in cephalopod adapting to fluctuating environments

Research Project

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Project/Area Number	19H03029
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Review Section	Basic Section 40030:Aquatic bioproduction science-related
Research Institution	The University of Tokyo
Principal Investigator	Iwata Yoko 東京大学, 大気海洋研究所, 准教授 (60431342)
Co-Investigator(Kenkyū-buntansha)	入江貴博東京大学, 大気海洋研究所, 助教 (30549332)
Project Period (FY)	2019-04-01 – 2023-03-31
Keywords	資源生態学 / イカ / 生活史 / 表現型可塑性
Outline of Final Research Achievements	To elucidate the environmental responses of life histories of Swordtip squid and Spear squid, we analyzed genetic population structure, compared life history traits among regional and seasonal populations, estimated experienced environmental conditions through life history by trace element analysis, and examined the mechanism of phenotypic determination. The Swordtip squid was genetically uniform from Taiwan to Japan, except for Tanegashima, and the reproductive traits and growth rate differed significantly among regional and seasonal populations. Trace element analysis suggested that the regional populations of the Swordtip squid compose a meta-population, with Taiwanese and further southern populations as a source and Japanese population as a sink population. Furthermore, hatching date was found to have a strong influence on the reproductive tactics of male Spear squid, indicating the importance of environmental conditions in the early life history for phenotypic determination.
Free Research Field	海洋生態学
Academic Significance and Societal Importance of the Research Achievements	本研究によって1) ケンサキイカの生活史特性は海洋環境条件によって大きく変化し、成熟齢やサイズ、産卵生態の変化を通じ資源量へ影響すること、2) ケンサキイカの個体群は台湾以南がsource、日本がsinkとなるメタ個体群の構造を持っていること、3)ヤリイカの成熟時に見られる表現型多型は孵化日によって決定されており生活史のごく初期の環境条件が重要であることが明らかとなった。本研究で得られた知見は、適正な漁業管理と資源予測を通じ、水産資源の持続可能な利用に寄与することが期待され、また気候変動が沿岸漁業対象種の表現型、ひいてはバイオマスに及ぼす影響を予測する上で役立つと考えられる。