Sexual conflict and intrasexual polymorphism promote assortative mating and halts population differentiation

Sexual conflict is thought to be an important evolutionary force in driving phenotypic diversification, population divergence and speciation. However, empirical evidence is inconsistent with the generality of sexual conflict as enhancing population divergence. Here we demonstrate an alternative evolutionary outcome in which sexual conflict plays a conservative role in maintaining male and female polymorphisms locally, rather than promoting population divergence. In diving beetles, female polymorphisms have evolved in response to male mating harassment and sexual conflict. We present the first empirical evidence that this female polymorphism is associated with 1) two distinct and sympatric male morphological mating clusters (morphs) and 2) assortative mating between male and female morphs. Changes in mating traits in one sex led to a predictable change in the other sex which leads to predictable within-population evolutionary dynamics in male and female morph frequencies. Our results rev...

性冲突（sexual conflict）被认为是推动表型多样化（phenotypic diversification）、种群分化（population divergence）与物种形成（speciation）的重要进化驱动力。然而，相关实证证据并不支持性冲突能够普遍促进种群分化这一论断。本研究揭示了一种全新的进化结局：性冲突在此过程中发挥保守作用，维持局域种群内雌雄两性的多态性（polymorphism），而非推动种群分化。在潜水甲虫中，雌性多态性的演化是对雄性交配骚扰与性冲突的适应性响应。我们首次提供实证证据表明，该雌性多态性与两点存在关联：1）两种形态迥异且同域分布（sympatric）的雄性交配形态类群（morphs）；2）雌雄形态型之间的选型交配（assortative mating）。某一性别的交配特征发生改变，可预见性地引发另一性别的对应变化，进而使得雌雄形态型频率在种群内产生可预测的进化动态。我们的研究结果……