Does hybridization induce adaptive radiation? Testing the "transgressive segregation" hypothesis using endemic gastropods in ancient Lake Biwa as a model system

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K15866
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 45030:Biodiversity and systematics-related
• Research Institution: Tohoku University (2022); Toho University (2020-2021)
• Principal Investigator: Saito Takumi 東北大学, 東北アジア研究センター, 学術研究員 (90858903)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 交雑 / 琵琶湖 / モノアラガイ / 多様化 / 外来種

Outline of Final Research Achievements

Radix japonica and their related lineages were sampled from Lake Biwa and throughout East Asia, and comprehensive genetic analysis was conducted using DNA data obtained from a high throughput sequencer. The shell morphology and ecology of these snails were also investigated and examined. Then, the results strongly suggest past hybridization between different lineages in Lake Biwa, and morphological analysis revealed the existence of the high morphological diversity in Lake Biwa that is not observed in other parts of the Japanese archipelago. In addition, the divergence time estimation suggests that geological changes in Lake Biwa may be the cause of the hybridization. Although further studies on plasticity and cause-and-effect relationship are needed, the results may support the possibility that hybridization is the driving force of evolutionary diversification.

Free Research Field

進化生態学・保全生物学・系統分類学

Academic Significance and Societal Importance of the Research Achievements

交雑が進化的な動態に与える影響は未知の点が多く、進化生態学上の重要課題であった。今回、交雑が進化的多様化に正の影響を与える可能性があることが網羅的なスケールでの遺伝解析から示唆された。また、従来あまり考慮されていなかった、生物地理学的な文脈の中で交雑を考慮することが重要であることが本研究により明らかになった。一方、本研究ではモノアラガイにおいて、多くの外来系統が日本列島に侵入していることも判明した。このような種内系統の隠蔽的な侵入は従来検出が難しくあまり着目されていなかったが、生物多様性の保全や進化動態への影響を考える上でも重要な知見であると考えられる。