Data from: Reciprocal interaction matrix reveals complex genetic and dose-dependent specificity among coinfecting parasites

Understanding genetic specificity in factors determining the outcome of host-parasite interactions is especially important as it contributes to parasite epidemiology, virulence, and maintenance of genetic variation. Such specificity, however, is still generally poorly understood. We examined genetic specificity in interactions among coinfecting parasites. In natural populations, individual hosts are often simultaneously infected by multiple parasite species and genotypes that interact. Such interactions could maintain genetic variation in parasite populations if they are genetically specific so that the relative fitness of parasite genotypes varies across host individuals depending on (1) the presence/absence of coinfections and/or (2) the genetic composition of the coinfecting parasite community. We tested these predictions using clones of fish eye flukes Diplostomum pseudospathaceum and Diplostomum gasterostei. We found that interactions among parasites had a strong genetic basis and that this modified genetic variation in infection success of D. pseudospathaceum between single and multiple infections as well as across multiply infected host individuals depending on the genetic identity of the coinfecting D. gasterostei. The relative magnitude of these effects, however, depended on the exposure dose, suggesting that ecological factors can modify genetic interactions between parasites.

阐明决定宿主-寄生虫相互作用（host-parasite interactions）结局的相关因子中的遗传特异性（genetic specificity），对于寄生虫流行病学（epidemiology）、毒力（virulence）以及种群遗传变异（genetic variation）的维持均具有至关重要的意义。然而，当前学界对这类遗传特异性的整体认知仍较为有限。我们针对共侵染寄生虫（coinfecting parasites）之间的遗传特异性开展了研究。在自然种群中，单个宿主通常会同时被多种寄生虫物种与基因型侵染，不同寄生虫之间会发生相互作用。若此类相互作用具备遗传特异性，即寄生虫基因型的相对适合度（relative fitness）会因宿主个体而异，具体取决于（1）是否存在共侵染（coinfections），以及（2）共侵染寄生虫群落（coinfecting parasite community）的遗传组成，那么这类相互作用或可维持寄生虫种群的遗传变异。我们利用鱼眼吸虫的两个克隆株系——假狭腹双穴吸虫（Diplostomum pseudospathaceum）与加斯氏双穴吸虫（Diplostomum gasterostei）——对上述预测进行了实验验证。研究结果显示，寄生虫间的相互作用具有较强的遗传基础，且该基础会改变假狭腹双穴吸虫在单一侵染与多重侵染情境下侵染成功率（infection success）的遗传变异；同时，在发生多重侵染的宿主个体间，假狭腹双穴吸虫侵染成功率的遗传变异也会随共侵染的加斯氏双穴吸虫的遗传特征发生显著变化。不过，上述效应的相对强度取决于暴露剂量（exposure dose），这表明生态因子（ecological factors）可对寄生虫间的遗传相互作用起到调控作用。