How parasite interaction strategies alter virulence evolution in multi-parasite communities

The majority of organisms host multiple parasite species, each of which can interact with hosts and competitors through a diverse range of direct and indirect mechanisms. These within-host interactions can directly alter the mortality rate of coinfected hosts and alter the evolution of virulence (parasite induced host mortality). Yet we still know little about how within-host interactions affect the evolution of parasite virulence in multi-parasite communities. Here, we modeled the virulence evolution of two coinfecting parasites in a host population in which parasites interacted through cross immunity, immune suppression, immunopathology, or spite. We show (1) that these within-host interactions have different effects on virulence evolution when all parasites interact with each other in the same way vs. when coinfecting parasites have unique interaction strategies, (2) that all of these interactions cause the evolution of lower virulence in some hosts, and higher virulence in other ho...

绝大多数宿主都会携带多种寄生虫物种，每一种寄生虫均可通过多样的直接与间接机制与宿主及竞争者发生相互作用。这些宿主内的相互作用可直接改变共感染宿主的死亡率，并改变毒力（virulence，即寄生虫诱导的宿主死亡）的演化进程。然而目前学界对宿主内相互作用如何影响多寄生虫群落中寄生虫毒力的演化仍知之甚少。本研究针对宿主种群中两种共感染寄生虫的毒力演化构建了模型，其中寄生虫可通过交叉免疫、免疫抑制、免疫病理或恶意相互作用（spite）发生相互作用。本研究结果表明：（1）当所有寄生虫以相同方式彼此相互作用时，这类宿主内相互作用对毒力演化的影响，与共感染寄生虫拥有独特相互作用策略时的影响存在显著差异；（2）上述所有相互作用均会导致部分宿主演化出更低的毒力，而在另一部分宿主则演化出更高的毒力……