Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland.
Department of Mathematics and Statistics, Department of Biology Queen's University, Kingston, Ontario, Canada.
Evolution. 2019 May;73(5):872-882. doi: 10.1111/evo.13718. Epub 2019 Mar 25.
Sterility virulence, or the reduction in host fecundity due to infection, occurs in many host-pathogen systems. Notably, sterility virulence is more common for sexually transmitted infections (STIs) than for directly transmitted pathogens, while other forms of virulence tend to be limited in STIs. This has led to the suggestion that sterility virulence may have an adaptive explanation. By focusing upon finite population models, we show that the observed patterns of sterility virulence can be explained by consideration of the epidemiological differences between STIs and directly transmitted pathogens. In particular, when pathogen transmission is predominantly density invariant (as for STIs), and mortality is density dependent, sterility virulence can be favored by demographic stochasticity, whereas if pathogen transmission is predominantly density dependent, as is common for most directly transmitted pathogens, sterility virulence is disfavored. We show these conclusions can hold even if there is a weak selective advantage to sterilizing.
不育毒力，或感染导致宿主繁殖力下降，在许多宿主-病原体系统中都存在。值得注意的是，不育毒力在性传播感染（STI）中比直接传播病原体更为常见，而其他形式的毒力往往在 STI 中受到限制。这导致了这样一种假设，即不育毒力可能具有适应性解释。通过关注有限种群模型，我们表明，观察到的不育毒力模式可以通过考虑 STI 和直接传播病原体之间的流行病学差异来解释。特别是，当病原体传播主要是密度不变时（如 STI 中），而死亡率是密度依赖时，不育毒力可以通过人口随机性来促进，而如果病原体传播主要是密度依赖时，这在大多数直接传播病原体中很常见，不育毒力则不受青睐。我们表明，即使对绝育有微弱的选择优势，这些结论也仍然成立。
