Ashby Ben, Boots Michael
Biosciences, College of Life and Environmental Sciences, University of Exeter, Cornwall Campus, Penryn, Cornwall, TR10 9EZ, United Kingdom;
Biosciences, College of Life and Environmental Sciences, University of Exeter, Cornwall Campus, Penryn, Cornwall, TR10 9EZ, United Kingdom; Integrative Biology, University of California, Berkeley, CA 94720.
Proc Natl Acad Sci U S A. 2015 Oct 27;112(43):13290-5. doi: 10.1073/pnas.1508397112. Epub 2015 Oct 1.
Parasites are thought to play an important role in sexual selection and the evolution of mating strategies, which in turn are likely to be critical to the transmission and therefore the evolution of parasites. Despite this clear interdependence we have little understanding of parasite-mediated sexual selection in the context of reciprocal parasite evolution. Here we develop a general coevolutionary model between host mate preference and the virulence of a sexually transmitted parasite. We show when the characteristics of both the host and parasite lead to coevolutionarily stable strategies or runaway selection, and when coevolutionary cycling between high and low levels of host mate choosiness and virulence is possible. A prominent argument against parasites being involved in sexual selection is that they should evolve to become less virulent when transmission depends on host mating success. The present study, however, demonstrates that coevolution can maintain stable host mate choosiness and parasite virulence or indeed coevolutionary cycling of both traits. We predict that choosiness should vary inversely with parasite virulence and that both relatively long and short life spans select against choosy behavior in the host. The model also reveals that hosts can evolve different behavioral responses from the same initial conditions, which highlights difficulties in using comparative analysis to detect parasite-mediated sexual selection. Taken as a whole, our results emphasize the importance of viewing parasite-mediated sexual selection in the context of coevolution.
寄生虫被认为在性选择和交配策略的进化中发挥着重要作用，而交配策略反过来可能对寄生虫的传播至关重要，因此也对寄生虫的进化至关重要。尽管存在这种明显的相互依存关系，但我们对互惠寄生虫进化背景下寄生虫介导的性选择了解甚少。在此，我们构建了一个宿主配偶偏好与性传播寄生虫毒力之间的一般协同进化模型。我们展示了宿主和寄生虫的特征何时会导致协同进化稳定策略或失控选择，以及宿主配偶选择度和毒力的高低水平之间何时可能发生协同进化循环。一个反对寄生虫参与性选择的突出观点是，当传播取决于宿主交配成功率时，它们应该进化得毒性更小。然而，本研究表明，协同进化可以维持稳定的宿主配偶选择度和寄生虫毒力，或者实际上维持这两个性状的协同进化循环。我们预测，选择度应与寄生虫毒力成反比，并且相对长和短的寿命都会对宿主的选择行为产生不利影响。该模型还揭示，宿主可以从相同的初始条件进化出不同的行为反应，这凸显了使用比较分析来检测寄生虫介导的性选择的困难。总体而言，我们的结果强调了在协同进化背景下看待寄生虫介导的性选择的重要性。
