Mountains have a long history in the study of diversity. Like macroscopic taxa, soil microbes are hypothesized to be strongly structured by montane gradients, and recently there has been important progress in understanding how microbes are shaped by these conditions. Here, we summarize this literature and synthesize patterns of microbial diversity on mountains. Unlike flora and fauna that often display a mid-elevation peak in diversity, we found a decline (34% of the time) or no trend (33%) in total microbial diversity with increasing elevation. Diversity of functional groups also varied with elevation (e.g. saprotrophic fungi declined 83% of the time). Most studies (82%) found that climate and soils (especially pH) were the primary mechanisms driving shifts in composition, and drivers differed across taxa—fungi were mostly determined by climate, while bacteria (48%) and archaea (71%) were structured primarily by soils. We hypothesize that the central role of soils—which can vary independently of other abiotic and geographic gradients—in structuring microbial communities weakens diversity patterns expected on montane gradients. Moving forward, we need improved cross-study comparability of microbial diversity indices (i.e. standardizing sequencing) and more geographic replication using experiments to broaden our knowledge of microbial biogeography on global gradients.

中文翻译：

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山地梯度上土壤微生物的多样性和功能：不断变化的世界中的知识状态。

山区在研究多样性方面历史悠久。像宏观类群一样，土壤微生物被认为是由山地梯度强烈构成的，最近在了解微生物如何受这些条件影响下取得了重要进展。在这里，我们总结了这些文献并综合了山区微生物多样性的模式。与动植物多样性通常在多样性中处于高峰的高峰不同，我们发现总微生物多样性随海拔升高而下降（34％的时间）或没有趋势（33％）。官能团的多样性也随海拔的升高而变化（例如，腐养真菌下降了83％）。大多数研究（82％）发现，气候和土壤（尤其是pH）是驱动成分变化的主要机制，并且不同分类单元的驱动力有所不同-真菌主要由气候决定，细菌（48％）和古细菌（71％）主要由土壤构成。我们假设土壤的结构（可以独立于其他非生物和地理梯度而变化）在构造微生物群落中的核心作用削弱了山地梯度所期望的多样性模式。展望未来，我们需要改善微生物多样性指数的跨研究可比性（即标准化测序），并通过实验扩大地理上的重复性，以扩大我们对全球梯度上微生物生物地理学的了解。