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Evolution of chirality in a land snails shell

Research Project

Project/Area Number 21H02556
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Review Section Basic Section 45040:Ecology and environment-related
Research InstitutionTohoku 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
Project Status Completed (Fiscal Year 2023)
Budget Amount *help
¥17,290,000 (Direct Cost: ¥13,300,000、Indirect Cost: ¥3,990,000)
Fiscal Year 2023: ¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000)
Fiscal Year 2022: ¥5,720,000 (Direct Cost: ¥4,400,000、Indirect Cost: ¥1,320,000)
Fiscal Year 2021: ¥6,630,000 (Direct Cost: ¥5,100,000、Indirect Cost: ¥1,530,000)
Keywords多様性 / 軟体動物 / 生態 / 進化 / 種分化 / 陸貝 / 変異 / 種形成 / 生殖的隔離 / 非対称性 / 巻き方 / 多型
Outline of Research at the Start

生物の非対称な形が左右反転すると何が起きるか。鏡像体はなぜ進化するのか。本研究は殻の左巻き・右巻きの鏡像変異をもつ陸生巻貝Euhadra属をモデルとしてこの謎に挑む。従来巻貝で知られる巻き方向決定遺伝子は、疾患として生じる左巻きについてであり、正常な左巻き・右巻きの違いを決める遺伝子とその進化過程は未知である。左巻き・右巻き集団の種分化機構も不明である。本研究では、ゲノム解析と交配実験により巻き方向を決める遺伝子を推定する。系統推定と交配実験から、鏡像変異間に段階的に生殖的隔離が進化する、という仮説を検証する。以上より巻き方における左右反転の進化過程を、ミクロ・マクロのレベルで理解する。

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.

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。

Report

(4 results)
  • 2023 Annual Research Report   Final Research Report ( PDF )
  • 2022 Annual Research Report
  • 2021 Annual Research Report
  • Research Products

    (5 results)

All 2023 2022 Other

All Int'l Joint Research (2 results) Journal Article (3 results) (of which Int'l Joint Research: 2 results,  Peer Reviewed: 3 results,  Open Access: 2 results)

  • [Int'l Joint Research] University of Nottingham(英国)

    • Related Report
      2023 Annual Research Report
  • [Int'l Joint Research] University of nottingham(英国)

    • Related Report
      2022 Annual Research Report
  • [Journal Article] Overcoming the congenitally disadvantageous mutation through adaptation to environmental UV exposure in land snails2023

    • Author(s)
      Ito S, Chiba S, Konuma J
    • Journal Title

      Biology Letters

      Volume: 19 Pages: 20230356-20230356

    • Related Report
      2023 Annual Research Report
    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Molecular investigation on diversity of the land snail genus Aegista (Gastropoda, Camaenidae) in South Korea2023

    • Author(s)
      Kimura Kazuki、Chiba Satoshi、Pak Jae-Hong
    • Journal Title

      Biodiversity Data Journal

      Volume: 11

    • DOI

      10.3897/bdj.11.e96800

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Sexual inactivation induced by the mucus that covers love-darts of a land snail: Sexual selection and evolution of allohormones in hermaphrodites.2022

    • Author(s)
      Kaito Shibuya, Satoshi Chiba, Kazuki Kimura
    • Journal Title

      The Journal of experimental biology

      Volume: 225 Issue: 4

    • DOI

      10.1242/jeb.238782

    • Related Report
      2021 Annual Research Report
    • Peer Reviewed

URL: 

Published: 2021-04-28   Modified: 2025-01-30  

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