Data from: Migration highways and migration barriers created by host-parasite interactions

Coevolving parasites may play a key role in host migration and population structure. Using coevolving bacteria and viruses, we test general hypotheses as to how coevolving parasites affect the success of passive host migration between habitats that can support different intensities of host-parasite interactions. First, we show that parasites aid migration from areas of intense to weak coevolutionary interactions and impede migration in the opposite direction, as a result of intraspecific apparent competition mediated via parasites. Second, when habitats show qualitative difference such that some environments support parasite persistence while others do not, different population regulation forces (either parasitism or competitive exclusion) will reduce the success of migration in both directions. Our study shows that coevolution with parasites can predictably homogenizes or isolates host populations, depending on heterogeneity of abiotic conditions, with the second scenario constituting a novel type of “isolation by adaptation”.

协同进化寄生虫（coevolving parasites）可能在宿主迁移与种群结构形成中发挥关键作用。本研究以协同进化的细菌与病毒为实验材料，检验关于协同进化寄生虫如何影响不同生境间被动宿主迁移（passive host migration）成功率的一般性假说，这些生境可支撑强度各异的宿主-寄生虫相互作用（host-parasite interactions）。首先，研究发现：由于寄生虫介导的种内表观竞争（intraspecific apparent competition），寄生虫会促进宿主从强协同进化相互作用区域向弱协同进化相互作用区域迁移，却阻碍反向迁移。其次，当生境存在质性差异，即部分环境可维持寄生虫存续，而另一部分则无法维持时，不同的种群调控因子（寄生虫寄生作用或竞争排除（competitive exclusion）会降低双向迁移的成功率。本研究表明，与寄生虫的协同进化可依据非生物条件（abiotic conditions）的异质性，可预测地使宿主种群发生同质化或隔离；其中第二种情形构成了一种新型的"适应性隔离（isolation by adaptation）"。