Why do some regions share more or fewer species than others? Community assembly relies on the ability of individuals to disperse, colonize and thrive in new regions. Therefore, many distinct factors, such as geographic distance and environmental features, can determine the odds of a species colonizing a new environment. For parasites, host community composition (i.e. resources) also plays a key role in their ability to colonize a new environment as they rely on their hosts to complete their life cycle. Thus, variation in host community composition and environmental conditions should determine parasite turnover among regions. Here, we explored the global drivers of parasite turnover using avian malaria and malaria-like (haemosporidian) parasites. We compiled global databases on avian haemosporidian lineages distributions, environmental conditions, avian species distributions and functional traits, and ran generalized dissimilarity models to uncover the main drivers of parasite turnover. We demonstrated that haemosporidian parasite turnover is mainly driven by geographic distance followed by host functional traits, environmental conditions and host distributions. The main host functional traits associated with high parasite turnover were the predominance of resident (i.e. non-migratory) species and strong territoriality, while the most important climatic drivers of haemosporidian turnover were mean temperature and temperature seasonality. Overall, we established the importance of geographic distance as a key predictor of ecological dissimilarity and showed that host resources influence parasite turnover more strongly than environmental conditions. We also evidenced that parasite turnover is most pronounced among tropical and less interconnected regions (i.e. regions with mostly territorial and non-migratory hosts). Our findings provide a robust foundation for the prediction of avian pathogen spread and the emergence of infectious diseases.

中文翻译：

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揭示寄生虫群落组装的驱动因素：使用鸟类血孢子虫模拟寄生虫物种更替的全球动态

为什么有些地区的物种比其他地区多或少？社区集会依赖于个人在新地区分散、殖民和繁荣的能力。因此，许多不同的因素，例如地理距离和环境特征，可以决定一个物种在新环境中定居的几率。对于寄生虫来说，宿主群落组成（即资源）在它们在新环境中定居的能力中也起着关键作用，因为它们依赖宿主来完成它们的生命周期。因此，寄主群落组成和环境条件的变化应决定区域间的寄生虫周转率。在这里，我们使用禽疟疾和类疟疾（血孢子虫）寄生虫探索了寄生虫更新的全球驱动因素。我们编制了关于鸟类血孢子虫谱系分布、环境条件、鸟类物种分布和功能特征，并运行广义差异模型以揭示寄生虫周转的主要驱动因素。我们证明了血孢子虫寄生虫的更替主要受地理距离的驱动，其次是宿主功能特征、环境条件和宿主分布。与高寄生虫周转率相关的主要宿主功能特征是常驻（即非迁徙）物种占优势和强地域性，而血孢子虫周转率最重要的气候驱动因素是平均温度和温度季节性。总的来说，我们确定了地理距离作为生态差异的关键预测指标的重要性，并表明宿主资源对寄生虫周转的影响比环境条件更强烈。我们还证明寄生虫更替在热带和相互联系较少的地区（即主要是领土和非迁徙宿主的地区）最为明显。我们的研究结果为预测禽病原体传播和传染病的出现提供了坚实的基础。