Predation-associated divergence of male genital morphology in a livebearing fish

Male genital morphology is remarkably diverse across internally fertilizing animals, a phenomenon largely attributed to sexual selection. Ecological differences across environments can alter the context of sexual selection, yet little research has addressed how this may influence the rapid, divergent evolution of male genitalia. Using the model system of Bahamas mosquitofish (Gambusia hubbsi) undergoing ecological speciation across blue holes, we used geometric morphometric methods to test (i) whether male genital shape (the small, approximately 1 mm long, distal tip of the sperm-transfer organ, the gonopodium) has diverged between populations with and without predatory fish and (ii) whether any observed divergence has a genetic basis. We additionally examined the effects of genetic relatedness and employed model selection to investigate other environmental factors (i.e. interspecific competition, adult sex ratio and resource availability) that could potentially influence genital shape ...

体内受精动物的雄性生殖器形态多样性极为显著，这一现象在很大程度上可归因于性选择（sexual selection）。不同环境下的生态差异会改变性选择的作用情境，但目前鲜有研究探讨这一过程如何影响雄性生殖器的快速趋异演化。本研究以跨蓝洞（blue holes）发生生态物种形成的巴哈马食蚊鱼（Gambusia hubbsi）为模式系统，采用几何形态测量法（geometric morphometric methods）开展两项验证：其一，雄性生殖器形态——即精子传递器官生殖足（gonopodium）长约1毫米的远端尖端——是否在有捕食性鱼类和无捕食性鱼类的种群间发生了分化；其二，观测到的形态分化是否具有遗传基础。此外，本研究还考察了遗传亲缘关系的影响，并通过模型筛选来探究其他可能影响生殖器形态的环境因素（即种间竞争、成年性比与资源可获得性）……