Evolution of chirality in a land snails shell

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H02556
• 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: Tohoku University
• Principal Investigator: Chiba Satoshi 東北大学, 東北アジア研究センター, 教授 (10236812)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 多様性 / 軟体動物 / 生態

Outline of Final Research Achievements

We obtained and assembled the whole genome data of Bradybaena and Euhadra. The total genome size of the former was 1.9 Gb, and chromosome-level assembly and annotation were performed. It was estimated that the reproductive isolation between the sinistral and dextral populations of E. quaesita exists at different levels. When there are no barriers to gene flow between the two, in addition to hybridization between the variants, the effects of delayed inheritance are also considered significant. In Aegista, it was shown that the sinistral lineage evolved from the dextral lineage in Korea, and it is estimated that in Bradybaena, the inistral form repeatedly arose independently in China. If no hybridization occurs between the sinistral and dextral individuals of E. quaesita, their shape and niche utilization have diverged.

Free Research Field

生態学

Academic Significance and Societal Importance of the Research Achievements

従来、左巻き個体からなる陸貝種の祖先は、右巻き野生型との交配が困難で繁殖に不利な突然変異として右巻き集団中に出現したと考えられてきたが、左巻き種の祖先は右巻き野生型に対し、交配可能でほぼ中立な突然変異として集団中に出現し、二型として存続したのち右巻きとの交配が困難になったという独自のシナリオを提案することができた。またこれに生態学的な気候が関わることも示せた点で生態学的な意義も大きい。この仮説を裏付けるミクロの機構は、今回実証できなかったが、そのベースとなる全ゲノムのアセンブルに成功し、アノテーションが進んだため、今後この問題を解決し、生物学の幅広い領域にインパクトを及ぼすと期待できる。