The evolutionary maintenance of sexual reproduction has long challenged biologists as the majority of species reproduce sexually despite inherent costs. Providing a general explanation for the evolutionary success of sex has thus proven difficult and resulted in numerous hypotheses. A leading hypothesis suggests that antagonistic species interaction can generate conditions selecting for increased sex due to the production of rare or novel genotypes that are beneficial for rapid adaptation to recurrent environmental change brought on by antagonism. To test this ecology‐based hypothesis, we conducted experimental evolution in a predator (rotifer)–prey (algal) system by using continuous cultures to track predator–prey dynamics and in situ rates of sex in the prey over time and within replicated experimental populations. Overall, we found that predator‐mediated fluctuating selection for competitive versus defended prey resulted in higher rates of genetic mixing in the prey. More specifically, our results showed that fluctuating population sizes of predator and prey, coupled with a trade‐off in the prey, drove the sort of recurrent environmental change that could provide a benefit to sex in the prey, despite inherent costs. We end with a discussion of potential population genetic mechanisms underlying increased selection for sex in this system, based on our application of a general theoretical framework for measuring the effects of sex over time, and interpreting how these effects can lead to inferences about the conditions selecting for or against sexual reproduction in a system with antagonistic species interaction.

中文翻译：

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敌对物种相互作用驱动捕食者-猎物系统中的性别选择

有性生殖的进化维持长期以来一直对生物学家提出挑战，因为尽管存在固有成本，但大多数物种还是有性繁殖。因此，为性的进化成功提供一般性解释已被证明是困难的，并导致了许​​多假设。一个主要假设表明，由于产生稀有或新基因型，有利于快速适应由拮抗作用引起的反复发生的环境变化，因此拮抗物种的相互作用可以产生选择增加性别的条件。为了验证这一基于生态学的假设，我们在捕食者（轮虫）-猎物（藻类）系统中进行了实验进化，方法是使用连续培养来跟踪捕食者-猎物动态以及猎物随时间和重复实验种群内的原位性别率. 全面的，我们发现，捕食者介导的对竞争性和防御性猎物的波动选择导致猎物的基因混合率更高。更具体地说，我们的结果表明，捕食者和猎物的种群规模波动，再加上猎物的权衡，推动了这种反复发生的环境变化，尽管存在固有成本，但可以为猎物的性别带来好处。我们最后讨论了该系统中增加性别选择的潜在种群遗传机制，基于我们应用的一般理论框架来衡量性别随时间的影响，并解释这些影响如何导致对选择条件的推断在具有敌对物种相互作用的系统中支持或反对有性生殖。