Turnover in species composition between sites, or beta diversity, is a critical component of species diversity that is typically influenced by geography, environment, and biotic interactions. Quantifying turnover is particularly challenging, however, in multi-host, multi-parasite assemblages where undersampling is unavoidable, resulting in inflated estimates of turnover and uncertainty about its spatial scale. We developed and implemented a framework using null models to test for community turnover in avian haemosporidian communities of three sky islands in the southwestern United States. We screened 776 birds for haemosporidian parasites from three genera (Parahaemoproteus, Plasmodium, and Leucocytozoon) by amplifying and sequencing a mitochondrial DNA barcode. We detected infections in 280 birds (36.1%), sequenced 357 infections, and found a total of 99 parasite haplotypes. When compared to communities simulated from a regional pool, we observed more unique, single-mountain haplotypes and fewer haplotypes shared among three mountain ranges than expected, indicating that haemosporidian communities differ to some degree among adjacent mountain ranges. These results were robust even after pruning datasets to include only identical sets of host species, and they were consistent for two of the three haemosporidian genera. The two more distant mountain ranges were more similar to each other than the one located centrally, suggesting that the differences we detected were due to stochastic colonization–extirpation dynamics. These results demonstrate that avian haemosporidian communities of temperate-zone forests differ on relatively fine spatial scales between adjacent sky islands. Null models are essential tools for testing the spatial scale of turnover in complex, undersampled, and poorly known systems.

站点之间物种组成的转变或β多样性是物种多样性的关键组成部分，通常受地理，环境和生物相互作用的影响。然而，在无法避免欠采样的多宿主，多寄生虫组合中，量化营业额特别具有挑战性，这会导致营业额估算过高以及其空间规模的不确定性。我们开发并实施了一个使用空模型的框架，以测试美国西南部三个天空岛的禽血孢子虫群落的群落更新。我们从三种属（副血红蛋白，疟原虫和白细胞虫）中筛选了776例禽流感寄生虫。）扩增和测序线粒体DNA条码。我们在280羽鸟类（36.1％）中检测到感染，对357例感染进行了测序，发现了总共99种寄生虫单倍型。与从区域库中模拟的社区相比，我们观察到三个山脉之间的独特，单峰单倍型和更少的单倍型比预期的要多，这表明在邻近山脉之间，血孢子虫群落有一定程度的差异。这些结果即使在将数据集修剪为仅包含相同宿主物种集之后仍然是可靠的，并且对于三个血友病属中的两个属也是一致的。距离较远的两个山脉比位于中心的山脉彼此更相似，这表明我们检测到的差异是由于随机的定殖-灭绝动力学所致。这些结果表明，温带区森林的鸟类造血孢子群落在相邻的天空岛之间的相对精细的空间尺度上有所不同。空模型是测试复杂，采样不足和鲜为人知的系统中营业额空间规模的重要工具。