Data from: Sexual conflict and STIs: coevolution of sexually antagonistic host traits with a sexually transmitted infection

In many taxa, there is a conflict between the sexes over mating rate. The outcome of sexually antagonistic coevolution depends on the costs of mating and natural selection against sexually antagonistic traits. A sexually transmitted infection (STI) changes the relative strength of these costs. We study the three-way evolutionary interaction between male persistence, female resistance, and STI virulence for two types of STIs: a viability-reducing STI and a reproduction-reducing STI. A viability-reducing STI escalates conflict between the sexes. This leads to increased STI virulence (i.e., full coevolution) if the costs of sexually antagonistic traits occur through viability but not if the costs occur through reproduction. In contrast, a reproduction-reducing STI de-escalates the sexual conflict but STI virulence does not coevolve in response. We also investigated the establishment probability of STIs under different combinations of evolvability. Successful invasion by a viability-reducing STI becomes less likely if hosts (but not parasite) are evolvable, especially if only the female trait can evolve. A reproduction-reducing STI can almost always invade because it does not kill its host. We discuss how the evolution of host and parasite traits in a system with sexual conflict differs from a system with female mate choice.

在诸多分类群中，两性间在交配频率上存在演化冲突。性拮抗协同进化的结局，取决于交配成本以及针对性拮抗性状的自然选择强度。性传播感染（sexually transmitted infection, STI）会改变这类成本的相对强弱。我们针对两类性传播感染，探究了雄性交配持续力、雌性交配抵抗性与STI毒力之间的三方进化交互作用：一类为降低宿主生存力的STI，另一类为降低宿主繁殖力的STI。降低宿主生存力的STI会加剧两性间的演化冲突：若性拮抗性状的成本通过生存力层面产生，则会推动STI毒力的进化（即完全协同进化）；若成本来自繁殖力层面，则不会出现该效应。与之相反，降低宿主繁殖力的STI会缓解性冲突，但STI毒力不会随之发生协同进化。我们还探究了不同可进化性组合下STI的定植概率。当宿主（而非寄生物）具备可进化性时，尤其是仅雌性性状可发生进化时，降低生存力的STI成功入侵宿主种群的概率会降低。而降低繁殖力的STI几乎总能成功入侵，因为它不会致死宿主。最后我们讨论了，存在性冲突的系统中，宿主与寄生物性状的进化模式，与存在雌性配偶选择的系统存在何种差异。