Morphological matching between male and female genitalia: deciphering the maintenance mechanisms by theoretical and empirical approaches

2018 Fiscal Year Final Research Report

• Project/Area Number: 15K07133
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Morphology/Structure
• Research Institution: Keio University
• Principal Investigator: KAMIMURA Yoshitaka 慶應義塾大学, 商学部(日吉), 准教授 (50366952)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: 微細手術 / 卵胎生昆虫 / 熱帯性昆虫 / 交尾器進化

Outline of Final Research Achievements

Recent studies have revealed that female genital morphology also rapidly evolve corresponding to the male genitals, which shows astonishing across-species diversity. There is ongoing debate on its underlying mechanisms, involving the two major hypotheses: the “sexual conflicts” and “cryptic female choice” hypotheses predict that exact matching of male and female genital morphologies reduces female mating costs or functions for choosing superior males, respectively.
This study tackled this problem from both theoretical and empirical approaches. In the latter, various insect groups were screened as potential model organisms for studying this topic. By surgically manipulating the female genital morphologies, studies on the fruit flies of the genus Drosophila revealed that (artificially induced) mismatching in male-female genitals during copulation can impose extensive costs on the female reproductive success, as it can hamper sperm transfer and the subsequent egg-laying.

Free Research Field

進化生物学

Academic Significance and Societal Importance of the Research Achievements

交尾器形態の進化は速いため、交尾器を観察なしでは種類を正確に同定できない動物も多い。特に種数の多い昆虫類では、交尾器形態の観察は、正確な同定や新種の記載に欠かせない作業である。
本研究が明らかにした「交尾器が正確に噛み合うことは、雌にとって重要である」という点は、雌雄の交尾器の形態が互いに影響を与えながら共進化・多様化していくプロセスの根底にあると考えられる。従来、雌の交尾器は観察が難しく、雄のそれに比べて多様性に乏しいと考えられてきたが、本研究の成果に基づき、雄交尾器形態に対応する部位を精査することで、雌サンプルのみでも正確に種同定できるケースが増えると期待される。