Data from: Resource predictability and specialization in avian malaria parasites

We tested the hypothesis that avian haemosporidian (malaria) parasites specialize on hosts that can be characterized as predictable resources at a site in Amazonian Ecuador. We incorporated host phylogenetic relationship and relative abundance in assessing parasite specialization, and we examined associations between parasite specialization and three host characteristics – abundance, mass and longevity – using quantile regression, phylogenetic logistic regression and t-tests. Hosts of specialist malaria parasite lineages were on average more abundant than hosts of generalist parasite lineages, but the relationship between host abundance and parasite specialization was not consistent across analyses. We also found support for a positive association between parasite specialization and host longevity, but this also was not consistent across analyses. Nonetheless, our findings suggest that the predictability of a host resource may play a role in the evolution of specialization. However, we also discuss two alternative explanations to the resource predictability hypothesis for specialization: (i) that interspecific interactions among the parasites themselves might constrain some parasites to a specialist strategy, and (ii) that frequent encounters with multiple host species, mediated by blood-sucking insects, might promote generalization within this system.我们检验了如下假说：在厄瓜多尔亚马逊地区的某一采样点，禽血孢子虫（avian haemosporidian，即鸟类疟原虫）会特异地寄居于可被界定为可预测资源的宿主类群。我们在评估寄生虫宿主特化程度时纳入了宿主的系统发育关系与相对丰度，并采用分位数回归、系统发育逻辑回归以及t检验，探究了寄生虫宿主特化程度与宿主三项特征——丰度、体重、寿命——之间的关联。特化型疟原虫谱系的宿主平均丰度高于泛化型疟原虫谱系的宿主，但宿主丰度与寄生虫宿主特化程度之间的关联在不同分析方法中并不一致。我们还发现寄生虫宿主特化程度与宿主寿命之间存在正相关的证据，但该关联在不同分析方法中同样不具备一致性。尽管如此，我们的研究结果表明，宿主资源的可预测性可能在宿主特化的演化过程中发挥了一定作用。不过，我们还针对宿主特化的资源可预测性假说提出了两种替代性解释：其一，寄生虫种间相互作用可能会限制部分寄生虫采取特化策略；其二，吸血昆虫介导的频繁接触多种宿主物种，可能会推动该系统内寄生虫向泛化方向演化。