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Abnormal molting? Male hermit crabs shrink their secondary sexual traits responding to predation risk

Research Project

Project/Area Number 25440238
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Research Field Ecology/Environment
Research InstitutionWakayama University

Principal Investigator

KOGA Tsunenori  和歌山大学, 教育学部, 教授 (50324984)

Co-Investigator(Kenkyū-buntansha) YOSHINO Kenji  佐賀大学, 低平地沿岸海域研究センター, 助教 (40380290)
Project Period (FY) 2013-04-01 – 2016-03-31
Project Status Completed (Fiscal Year 2015)
Budget Amount *help
¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000)
Fiscal Year 2015: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2014: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2013: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Keywords対捕食者反応 / 二次的性形質 / 自然淘汰 / 性淘汰 / ヤドカリ / 脱皮 / ストレス / 死亡率 / 季節変化
Outline of Final Research Achievements

Secondary sexual traits of males often involve risk of predation because of their conspicuousness. We got results in an experiment using a hermit crab species that only large males with relatively longer claws which are advantageous in inter-male competition for female mates decreased length of the claws by molting under high predation risk, but that small males or females did not. This change of large males may be adaptive to reduce predation risk and then enable to acquire more female mates. Decreasing size by molting is the opposite phenomenon, because molting is known for growing or regenerating the missing claws or legs in some crustaceans.
We conducted another experiment of similar design but increasing stress to hermit crabs. The survival rate of crabs with predator significantly dropped, while that without predator did not. The results indicated that not only predation itself but also existence of predator causes serious stress to the prey animals.

Report

(4 results)
  • 2015 Annual Research Report   Final Research Report ( PDF )
  • 2014 Research-status Report
  • 2013 Research-status Report

Research Products

(5 results)

All 2015 2014

All Presentation (5 results)

  • [Presentation] テナガツノヤドカリは捕食者の存在そのものにストレスを受けるか?2015

    • Author(s)
      深野祥平、古賀庸憲、吉野健児
    • Organizer
      日本動物行動学会第34回大会
    • Place of Presentation
      東京海洋大学
    • Year and Date
      2015-11-20
    • Related Report
      2015 Annual Research Report
  • [Presentation] テナガツノヤドカリDiogenes nitidimanusは捕食者の存在によりストレスを受けるか?2015

    • Author(s)
      深野祥平、古賀庸憲、吉野健児
    • Organizer
      2015年日本ベントス学会・日本プランクトン学会合同大会
    • Place of Presentation
      北海道大学
    • Year and Date
      2015-09-02
    • Related Report
      2015 Annual Research Report
  • [Presentation] テナガツノヤドカリの大形オスが繁殖期に脱皮して二次的性形質を縮小する2014

    • Author(s)
      井上明子、古賀庸憲、吉野健児
    • Organizer
      日本動物行動学会2014年度大会
    • Place of Presentation
      長崎大学(長崎市文教町1-14)
    • Year and Date
      2014-11-01 – 2014-11-03
    • Related Report
      2014 Research-status Report
  • [Presentation] The large claw shrinks by molting in response to predicted predation risk in male hermit crab Diogenes nitidimanus2014

    • Author(s)
      Koga T, Yoshino K, Inoue A, Sakata N
    • Organizer
      IAA (International Association of Astacology) & CSJ (The Carcinological Society of Japan) Joint International Conference on Crustacea
    • Place of Presentation
      北海道立道民活動センターかでる27および札幌円山動物園(札幌市中央区北2条西7丁目および中央区宮ヶ丘3-1)
    • Year and Date
      2014-09-20 – 2014-09-26
    • Related Report
      2014 Research-status Report
  • [Presentation] テナガツノヤドカリが対捕食者反応としてオスの二次的性形質を縮小する2014

    • Author(s)
      井上明子,深野祥平,*古賀庸憲(和歌山大・教育),吉野健児(佐賀大・低湿 地沿岸)
    • Organizer
      日本生態学会
    • Place of Presentation
      日本生態学会第61回全国大会
    • Related Report
      2013 Research-status Report

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Published: 2014-07-25   Modified: 2019-07-29  

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