Host heterogeneity mitigates virulence evolution
Host heterogeneity mitigates virulence evolution
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DOI：
10.1098/rsbl.2019.0744
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发表时间：
2020-01-29
期刊：
影响因子：
3.3
通讯作者：
Morran, Levi
中科院分区：
文献类型：
--
作者：
White, P. Signe;Choi, Angela;Morran, Levi
寄生虫通常感染遗传多样性的宿主群体，寄生虫群体的进化轨迹可能由宿主异质性水平决定。与同质宿主群体相比，混合基因型宿主群体可以降低寄生虫流行率，并且由于与适应特定宿主基因型相关的权衡而可能降低寄生虫适应率。在这里，我们使用实验进化来选择暴露于异质或同质秀丽隐杆线虫种群的细菌寄生虫粘质沙雷氏菌种群中毒力增加的情况。我们发现，暴露于异质宿主群体的寄生虫在数百个细菌世代中进化出的毒力明显低于暴露于同质宿主群体的寄生虫。因此，宿主异质性阻碍了寄生虫对宿主群体的适应。虽然我们检测到毒力进化中的权衡，但寄生虫对两种特定宿主基因型的适应也导致对相互宿主基因型的毒力适度增加。这些结果表明，寄生虫对异质宿主群体的适应可能会受到权衡和选择效率降低的阻碍，因为不同的宿主基因型对寄生虫群体施加不同的选择压力。
Parasites often infect genetically diverse host populations, and the evolutionary trajectories of parasite populations may be shaped by levels of host heterogeneity. Mixed genotype host populations, compared to homogeneous host populations, can reduce parasite prevalence and potentially reduce rates of parasite adaptation due to trade-offs associated with adapting to specific host genotypes. Here, we used experimental evolution to select for increased virulence in populations of the bacterial parasite Serratia marcescens exposed to either heterogeneous or homogeneous populations of Caenorhabditis elegans. We found that parasites exposed to heterogeneous host populations evolved significantly less virulence than parasites exposed to homogeneous host populations over several hundred bacterial generations. Thus, host heterogeneity impeded parasite adaptation to host populations. While we detected trade-offs in virulence evolution, parasite adaptation to two specific host genotypes also resulted in modestly increased virulence against the reciprocal host genotypes. These results suggest that parasite adaptation to heterogeneous host populations may be impeded by both trade-offs and a reduction in the efficacy of selection as different host genotypes exert different selective pressures on a parasite population.