| Project/Area Number |
17K07576
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Ecology/Environment
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| Research Institution | Kyoto Women's University |
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Principal Investigator |
Nakata Kensuke 京都女子大学, 現代社会学部, 教授 (80331031)
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| Co-Investigator(Kenkyū-buntansha) |
繁宮 悠介 長崎総合科学大学, 総合情報学部, 准教授 (00399213)
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| Project Period (FY) |
2017-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000)
Fiscal Year 2019: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2018: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2017: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
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| Keywords | クモ / 交尾器 / 性的対立 / 父性確保 / 繁殖 / 性選択 / 円網 / コスト / 交尾行動 / 精子利用 / 対向進化 / 適応度 / 繁殖生態 / 雌雄の対立 / 求愛 / 種間比較 / 出会い頻度 / 触肢 / 個体性 |
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| Outline of Final Research Achievements |
Details of External Female Genital Mutilation (EFGM) in orb web spiders were examined in Cyclosa argenteoalba. We found that females which received three palpal insertions had more viable eggs than females receiving two insertions, contralateral palpal insertions were necessary for successful EFGM, and the rate for a male which had mated with a female to encounter an additional female was ca. 30%. We also examined whether EFGM occurred and functioned to secure paternity in three congenus spiders, i.e., Cyclosa ginnaga, C. confusa, and C. octotuberculata. EFGM was found in the former two spiders. However, unexpectedly, the function of EFGM to secure paternity was not so significant as it was observed in C. argenteoalba. Additionally, EFGM was not found in C. octotuberculata, but the half of mated females failed the second mating. From these results, we consider that further investigation should be made to examine the hypothesis that EFGM evolved to secure paternity.
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| Academic Significance and Societal Importance of the Research Achievements |
クモのオスが交接の際にメスの交尾器を破壊する現象は、メスの交尾回数を巡るオスメスの利益が必ずしも一致しておらず、片方の性が相手の性の利益を損ないながら自己の利益を実現する性的対立の1事例であり、オスが優位に立つ働きを持つものとして進化してきたと考えられている。本研究の成果では、性的対立存在の条件である複数回交尾がメスに与える利益を確認したものの、メスが複数オスと交尾する機会そのものが少ないことが示唆された。また同属他種では交尾器破壊は父性確保の機能が小さいことがわかった。このことは、性的対立が特異な繁殖行動の進化に与える影響について更なる調査が必要であることを示唆している。
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