Does the direction of latitudinal adaptation govern variation in potential growth rate? A test using cold-water fishes

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K06207
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 40030:Aquatic bioproduction science-related
• Research Institution: Hiroshima University
• Principal Investigator: Tomiyama Takeshi 広島大学, 統合生命科学研究科(生), 准教授 (20576897)
• Co-Investigator(Kenkyū-buntansha): 米田 道夫 国立研究開発法人水産研究・教育機構, 水産技術研究所(廿日市), 主任研究員 (30450787) ; 海野 徹也 広島大学, 統合生命科学研究科(生), 教授 (70232890)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 緯度間変異 / 成長速度 / イカナゴ / マコガレイ

Outline of Final Research Achievements

To test the hypothesis that potential growth rates are higher in low-latitude populations of cold-water fishes, we examined growth responses of marbled flounder and the sand lance under excess food conditions. Experiments were conducted at water temperatures ranging from 14 to 23 °C using hatchery-reared marbled flounder from Ibaraki (high latitude) and Hiroshima (low latitude) prefectures. No differences were observed between populations in terms of maximum growth or optimal water temperature, but juveniles from the low-latitude population showed higher growth rates at high water temperatures 20 >°C. In the experiment using larval sand lance originating from the Seto Inland Sea (low latitude) and Sendai Bay (high latitude), the initial growth rate of the low-latitude population was higher than that of the high-latitude population under the same temperature and food conditions. Thus, the hypothesis of this research project was generally verified.

Free Research Field

水産資源生態学

Academic Significance and Societal Importance of the Research Achievements

同一種でも地域集団によって生物特性が異なる事例はしばしば観察されており、暖水性の魚類では高緯度の集団で潜在的成長速度が大きい（同じ水温環境で飼育した場合に、高緯度の集団の方がより大きく成長する）ことが知られていた。本研究では、冷水性魚類で逆の現象（低緯度の集団の方がよい大きく成長する）ことを示した。すなわち、冷水性魚類ではより高い水温環境である低緯度の方が厳しい環境であり、そこで潜在的な成長速度が大きくなるように適応している、という仮説を提唱できた。