Community Dynamics Group, Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, D-Plön, Germany.
J Evol Biol. 2020 Sep;33(9):1180-1191. doi: 10.1111/jeb.13658. Epub 2020 Jun 21.
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.
性繁殖的进化维持长期以来一直困扰着生物学家，因为尽管存在内在成本，但大多数物种仍然进行有性繁殖。因此，为性的进化成功提供一个普遍的解释变得非常困难，并导致了许多假说的产生。一个主要的假说表明，种间的相互拮抗作用可以产生选择增加性的条件，因为产生了罕见或新颖的基因型，这些基因型有利于快速适应由拮抗作用引起的反复环境变化。为了检验这一基于生态学的假说，我们在一个捕食者（轮虫）-猎物（藻类）系统中进行了实验进化，通过连续培养来追踪捕食者-猎物的动态，并在时间和重复的实验种群中实时跟踪猎物中的性发生速率。总的来说，我们发现，捕食者介导的对有竞争力和受保护猎物的波动选择导致了猎物中更高的遗传混合率。更具体地说，我们的结果表明，捕食者和猎物的种群大小波动，加上猎物的权衡，驱动了那种可能为猎物中的性带来好处的反复环境变化，尽管存在内在成本。最后，我们根据我们应用的一个一般理论框架来衡量性在时间上的影响，并解释这些影响如何导致对具有种间拮抗作用的系统中选择或反对性繁殖的条件的推断，讨论了在这个系统中增加性选择的潜在种群遗传机制。
