Habitat Heterogeneity, Host Population Structure, and Parasite Local Adaptation
Habitat Heterogeneity, Host Population Structure, and Parasite Local Adaptation
复制标题
栖息地异质性、寄主种群结构和寄生虫的局部适应
作者：
C. Lively
摘要相互移植实验已被证明是检测局部适应（LA）的有力工具。最近，互惠交叉接种实验已被用于评估寄生虫对其当地宿主种群的适应性。这些实验在概念上类似于相互移植实验，除了“环境”（宿主种群）可能会随着寄生虫种群的变化而进化。在这里，我使用分析工具和计算机模拟，以确定何时寄生虫预计将更具感染性的本地主机人口比异地主机人口。这些模型假设寄生虫必须在基因上与宿主“匹配”才能感染。我还假设不同的宿主克隆在不同的种群中受到青睐。当寄生虫毒力较低时，克隆选择超过寄生虫介导的选择，导致种群内宿主多样性较低，寄生虫的LA较强。在中等毒力水平下，寄生虫介导的选择在种群内维持了高水平的宿主多样性，从而减少或消除了寄生虫LA。寄生虫LA的损失与寄生虫对异域宿主的感染性增加无关。相反，LA的损失是由于减少寄生虫对同域宿主的感染性。最后，在高水平的寄生虫毒力下，寄生虫介导的选择导致振荡的宿主动态和寄生虫的弱局部适应。在所有水平的毒力，寄生虫LA的强度密切跟踪的程度，主机人口结构（GST）。
Abstract Reciprocal‐transplant experiments have proven to be a powerful tool for detecting local adaptation (LA). More recently, reciprocal cross‐inoculation experiments have been used to evaluate adaptation by parasites to their local host populations. These experiments are conceptually similar to reciprocal‐transplant experiments, except that the “environment” (the host population) may have evolved in response to changes in the parasite population. Here, I use analytical tools and computer simulations to determine when parasites would be expected to be more infective to their local host populations than to allopatric host populations. The models assume that parasites have to genetically “match” their hosts in order to infect. I also assumed that different host clones were favored in different populations. When parasite virulence was low, clonal selection outweighed parasite‐mediated selection, leading to low host diversity within populations and strong LA by parasites. At intermediate levels of virulence, parasite‐mediated selection maintained high levels of host diversity within populations, which reduced or eliminated parasite LA. The loss of parasite LA was not associated with increased infectivity by parasites on allopatric hosts. Instead, the loss of LA was due to a reduction in infectivity of parasites on sympatric hosts. Finally, at high levels of parasite virulence, parasite‐mediated selection led to oscillatory host dynamics and weak local adaption by parasites. Across all levels of virulence, the strength of parasite LA closely tracked the degree of host population structure (GST).