Sexual conflict is caused by differences between the sexes in how fitness is maximized. These differences are shaped by the discrepancy in the investment in gametes, how mates are chosen and how embryos and young are provided for. Fish in the family Poeciliidae vary from completely provisioning eggs before they are fertilized to providing virtually all resources after fertilization via the functional equivalent of a mammalian placenta. This shift in when females provision their young relative to when an egg is fertilized is predicted to cause a fundamental change in when and how sexual conflict is manifested. If eggs are provisioned before fertilization, there should be strong selection for females to choose with whom they mate. Maternal provisioning after fertilization should promote a shift to post-copulatory mate choice. The evolution of maternal provisioning may in turn have cascading effects on the evolution of diverse features of the biology of these fish because of this shift in when mates are chosen. Here we summarize what these consequences are and show that the evolution of maternal provisioning is indeed associated with and appears to govern the evolution of male traits associated with sexual selection. The evolution of placentas and associated conflict does not cause accelerated speciation, contrary to predictions. Accelerated sSpeciation rate is instead correlated with accelerated by the evolution of male traits associated with sexual selection, which implies a more prominent role of pre-copulatory reproductive isolation in causing speciation in this family.

中文翻译：

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繁殖方式和冲突决定着鱼类科Poeciliidae雄性属性和物种形成速率的演变。

性冲突是由两性之间在最大程度地提高健身能力方面的差异引起的。这些差异是由配子投资的差异，配偶的选择方式以及胚胎和幼体的提供方式所决定的。Poeciliidae家族中的鱼从受精前完全提供卵到受精后通过哺乳动物胎盘的功能等同物提供几乎所有资源，这些变化不一。预计雌性提供卵的时间相对于受精卵的时间发生变化，这将导致性冲突的发生时间和方式发生根本性变化。如果在受精前提供卵子，应该有很多选择供雌性选择与之交配的雌性。受精后的产妇调配应促进向交配后伴侣选择的转变。由于选择配偶时的这种转变，产妇供应的演变可能反过来对这些鱼类的生物学特性的演变具有连锁效应。在这里，我们总结了这些后果是什么，并表明孕产妇配置的演变确实与性选择相关的男性性状的演变有关，并且似乎支配着这些性状的演变。与预言相反，胎盘的演变和相关的冲突不会导致物种形成加速。相反，加速的sSpecification率与与性选择相关的男性性状的进化加速相关，这意味着交配前生殖隔离在引起该家庭的物种形成中具有更重要的作用。