The microbial communities living on and in vertebrate hosts have myriad effects on their hosts, potentially including fitness and speciation. Microbiomes are influenced by both intrinsic (from the host) and extrinsic (from the environment) factors, but the relative contributions of each are unknown for most non-model species. Abiotic environmental factors can influence the microbiome directly but it is less clear how abiotic gradients shape microbiome communities in the wild. Here, we captured eight wild Anna’s hummingbirds from three different elevations along their elevational distribution in California and moved them directly to a middle (“Within Range”) elevation. After some time at this elevation, the birds were moved in captivity to an “Above Range” elevation, and two birds were later moved back to the Within Range elevation. Fecal and food samples were collected longitudinally and the V4 region of the 16S rRNA gene analyzed. The most abundant phyla in all samples were Fusobacteria, Firmicutes, Actinobacteria, and Proteobacteria. Individual Bird ID explained the greatest amount of microbiome variation at 27.5%, signifying some amount of stability in the Anna’s hummingbird fecal microbiome. Sample elevation explained 19.6% (p = 0.001) of the variation using weighted UniFrac, but only 2.0% (p = 0.047) using unweighted UniFrac, implying a change in abundance of bacterial lineages in the microbiome but not in the presence or absence of the microbes. Additionally, Fusobacteria were 7.0x more abundant in the Above Range elevation samples while Firmicutes were 0.3x lower. A thorough understanding of how the environment can shape the microbiome may assist in conservation efforts and a general understanding of host-microbiome relationships in an era of rapid and global environmental change.

中文翻译：

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海拔与蜂鸟粪便微生物群相对丰度的显着变化相关，但组成变化不大

生活在脊椎动物宿主身上和体内的微生物群落对其宿主有无数影响，可能包括适应性和物种形成。微生物组受内在（来自宿主）和外在（来自环境）因素的影响，但对于大多数非模型物种而言，每种因素的相对贡献是未知的。非生物环境因素可以直接影响微生物群落，但尚不清楚非生物梯度如何塑造野外微生物群落。在这里，我们沿着加利福尼亚海拔分布的三个不同海拔捕获了八只野生安娜蜂鸟，并将它们直接移动到中间（“范围内”）海拔。在这个海拔一段时间后，这些鸟被圈养到“范围内”海拔，后来有两只鸟被移回范围内海拔。纵向收集粪便和食物样本并分析 16S rRNA 基因的 V4 区域。所有样品中最丰富的门是梭杆菌、厚壁菌门、放线菌和变形菌门。个体鸟类 ID 解释了最大量的微生物组变异，为 27.5%，表明安娜蜂鸟粪便微生物组具有一定程度的稳定性。样本升高使用加权 UniFrac 解释了 19.6% (p = 0.001) 的变化，但使用未加权 UniFrac 只有 2.0% (p = 0.047)，这意味着微生物组中细菌谱系的丰度发生了变化，但在存在或不存在微生物。此外，在高于范围的海拔样品中，梭杆菌多 7.0 倍，而厚壁菌则低 0.3 倍。