Data from: Migratory behavior predicts greater parasite diversity in ungulates

Long-distance animal movements can increase exposure to diverse parasites, but can also reduce infection risk through escape from contaminated habitats or culling of infected individuals. These mechanisms have been demonstrated within and between populations in single-host/single-parasite interactions, but how long-distance movement behaviors shape parasite diversity and prevalence across host taxa is largely unknown. Using a comparative approach, we analyze the parasite communities of 93 migratory, nomadic, and resident ungulate species. We find that migrants have higher parasite species richness than residents or nomads, even after considering other factors known to influence parasite diversity, such as body size and host geographic range area. Further analyses support a novel “environmental tracking” hypothesis, whereby migration allows parasites to experience environments favorable to transmission year-round. In addition, the social aggregation and large group sizes that facilitate migration might increase infection risk for migrants. In contrast, we find little support for previously-proposed hypotheses, including migratory escape and culling, in explaining the relationship between host movement and parasitism in mammals at this cross-species scale. Our findings, which support mechanistic links between long-distance movement and increased parasite richness at the species level, could help predict the effects of future environmental change on parasitism in migratory animals.长距离动物移动可提升宿主接触多种寄生虫的概率，但也可通过逃离污染栖息地或清除感染个体降低感染风险。这类调控机制已在单宿主/单寄生虫互作的种群内部及种群间得到验证，但长距离移动行为如何塑造不同宿主类群的寄生虫多样性与感染率，目前仍尚未明确。本研究采用比较研究法，分析了93种迁徙、游牧与定居有蹄类动物（Ungulates）的寄生虫群落。研究发现，即便在控制了已知影响寄生虫多样性的其他因素（如宿主体型与地理分布范围面积）后，迁徙物种的寄生虫物种丰富度仍高于游牧或定居物种。进一步分析支持一项全新的“环境追踪”假说：迁徙行为可使寄生虫全年处于利于传播的环境中。此外，支撑迁徙的社会聚集与大群规模，可能会提升迁徙物种的感染风险。与之相反，在跨物种尺度下解释哺乳动物宿主移动与寄生关系时，此前提出的迁徙逃逸、个体清除等假说几乎未得到本研究的支持。本研究证实了物种层面长距离移动与寄生虫丰富度提升之间存在机制性关联，相关发现或有助于预测未来环境变化对迁徙动物寄生状况的影响。