Molecular genetic mechanisms underlying life-history evolution and diversification

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H03277
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 45020:Evolutionary biology-related
• Research Institution: The University of Tokyo (2020-2021); National Institute of Genetics (2019)
• Principal Investigator: Ishikawa Asano 東京大学, 大学院新領域創成科学研究科, 准教授 (20722101)
• Co-Investigator(Kenkyū-buntansha): 山崎 曜 国立遺伝学研究所, ゲノム・進化研究系, 助教 (40816021) ; 北野 潤 国立遺伝学研究所, ゲノム・進化研究系, 教授 (80346105)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 季節性繁殖

Outline of Final Research Achievements

The annual timing of reproduction is a key life-history trait having a large effect on fitness. Populations often show convergent evolution of the reproductive period to adapt to different seasonality between habitats. To address the molecular genetic mechanisms, we use the three-spined stickleback as a model. We found that the multiple freshwater populations exhibited an extended breeding season. We showed that gonad development is suppressed by short photoperiod in marine ecotypes, but not in freshwater ecotypes. TSHb2 exhibited photoperiodic changes in marine ecotypes, but not in multiple freshwater populations. Knockout marine fish of TSHb2 demonstrated that fish showed signs of maturation even under short photoperiod. They were also similar to freshwater individuals in brain transcriptome and body size, suggesting pleiotropic effects. We revealed that the parallel loss of TSHb2 response occurred via different mechanisms; cis- and trans- mutations in Canada and Japan, respectively.

Free Research Field

進化生物学

Academic Significance and Societal Importance of the Research Achievements

甲状腺刺激ホルモンは、イトヨ以外の魚や鳥、哺乳類でも季節性繁殖の制御をおこなっていることが分かってきました。このため、広い生物群で季節性繁殖の進化の鍵を担っているハブ遺伝子として機能していると考えられます。この遺伝子を制御することにより、より長い期間繁殖する家畜種や養殖種の作成などが可能になる可能性があります。