Mechanical reproductive isolation facilitates parallel speciation in western North American scincid lizards

Mechanical reproductive barriers have been dismissed as a major driver of animal speciation, yet the extent to which such barriers cause reproductive isolation in most animal groups is largely unknown and rarely tested. In this study, we used hierarchical Bayesian modeling of mate compatibility experiments to show that body size divergence in lizards of the Plestiodon skiltonianus complex contributes to reproductive isolation in at least three ways: males preferably court females that are more similar in size, females reject males that are highly divergent in size, and that the size difference of a male and female in copula constrains the ability to align the genitalia for intromission. We used a predictive model to estimate the contributions of behavioral and mechanical barriers to reproductive isolation between populations with differing degrees of size divergence. This model shows that the mechanical barrier is more important than the behavioral barriers at small and intermediate deg...

机械生殖隔离屏障（mechanical reproductive barriers）曾被学界排除在动物物种形成核心驱动因素之外，但这类屏障在绝大多数动物类群中促成生殖隔离的具体程度，目前仍鲜为人知且极少得到实证验证。本研究通过对配偶兼容性实验开展分层贝叶斯建模（hierarchical Bayesian modeling），证实了五线石龙子复合群（Plestiodon skiltonianus complex）蜥蜴的体型分化，可通过至少三种途径促成生殖隔离：雄性更倾向于向体型更为相近的雌性求偶；雌性会拒绝体型差异显著的雄性；交配过程中雌雄个体的体型差，会限制二者生殖器对准以完成插入式交配（intromission）的能力。我们借助预测模型，估算了行为隔离屏障与机械生殖隔离屏障在不同体型分化程度的种群间对生殖隔离的贡献权重。该模型显示，在体型分化程度较小与中等的种群中，机械生殖隔离屏障的作用要优于行为隔离屏障……