Origins of female genital diversity: predation risk and lock-and-key explain rapid divergence during an adaptive radiation

The study of male genital diversity has long overshadowed evolutionary inquiry of female genitalia, despite its non-trivial diversity. Here we identify four non-mutually exclusive mechanisms that could lead to genital divergence in females, and potentially generate patterns of correlated male-female genital evolution: (1) ecological variation alters the context of sexual selection (“ecology hypothesis”), (2) sexually antagonistic selection (“sexual-conflict hypothesis”), (3) female preferences for male genitalia mediated by female genital traits (“female-choice hypothesis”), and (4) selection against inter-population mating (“lock-and-key hypothesis”). We performed an empirical investigation of all four hypotheses using the model system of Bahamas mosquitofish inhabiting blue holes that vary in predation risk. We found unequivocal support for the ecology hypothesis, with females exhibiting a smaller genital opening in blue holes containing piscivorous fish. This is consistent with stron...长期以来，雄性生殖器多样性的研究遮蔽了雌性生殖器演化的相关探究，尽管雌性生殖器本身具备不容忽视的多样性。本研究明确了四种非互斥机制，可引发雌性生殖器分化，并可能催生雌雄生殖器协同演化的模式：（1）生态变异改变性选择的作用背景（「生态假说（ecology hypothesis）」）；（2）性拮抗选择（「性冲突假说（sexual-conflict hypothesis）」）；（3）雌性凭借自身生殖器性状介导的对雄性生殖器的偏好（「雌性选择假说（female-choice hypothesis）」）；（4）针对种群间交配的选择（「锁钥假说（lock-and-key hypothesis）」）。我们以栖息于捕食风险各异的蓝洞（blue holes）的巴哈马食蚊鱼（Bahamas mosquitofish作为模型系统，对上述四种假说开展了实证检验。研究结果为生态假说提供了明确支持：在存在掠食性鱼类的蓝洞中，雌性的生殖器开口更小。这与 stron...