Frank S A
Department of Ecology and Evolutionary Biology, University of California, Irvine 92717.
Proc Biol Sci. 1992 Dec 22;250(1329):195-7. doi: 10.1098/rspb.1992.0149.
The costs and benefits of parasite virulence are analysed in an evolutionarily stable strategy (ESS) model. Increased host mortality caused by disease (virulence) reduces a parasite's fitness by damaging its food supply. The fitness costs of high virulence may be offset by the benefits of increased transmission or ability to withstand the host's defences. It has been suggested that multiple infections lead to higher virulence because of competition among parasite strains within a host. A quantitative prediction is given for the ESS virulence rate as a function of the coefficient of relatedness among co-infecting strains. The prediction depends on the quantitative relation between the costs of virulence and the benefits of transmission or avoidance of host defences. The particular mechanisms by which parasites can increase their transmission or avoid host defences also have a key role in the evolution of virulence when there are multiple infections.
在一个进化稳定策略（ESS）模型中分析了寄生虫毒力的成本和收益。由疾病（毒力）导致的宿主死亡率增加会通过损害其食物供应来降低寄生虫的适应性。高毒力的适应性成本可能会被传播增加或抵御宿主防御能力增强所带来的好处所抵消。有人提出，多重感染会导致更高的毒力，因为宿主内寄生虫菌株之间存在竞争。给出了ESS毒力率作为共感染菌株之间亲缘系数函数的定量预测。该预测取决于毒力成本与传播或避免宿主防御的好处之间的定量关系。当存在多重感染时，寄生虫增加其传播或避免宿主防御的具体机制在毒力进化中也起着关键作用。
