Microbial communities in natural ecosystems are subject to strong ecological rules. The study of local communities along a regional metacommunity can reveal patterns of community assembly, and disentangle the underlying ecological processes. In particular, we seek drivers of community assembly at the regional scale using a large lacustrine dataset (>300 lakes) along the geographical, limnological and physico-chemical gradients in the Pyrenees. By using high throughput amplicon sequencing of the 16S rRNA gene, and inferring environmental sources of bacterial immigrants, we showed that surface aquatic bacterial assemblages were strongly influenced by terrestrial populations from soil, biofilms or sediments, and primarily selected by a pH-alkalinity gradient. Indeed, source proportions explained 27% of the community variation, and chemistry 15% of the total variation, half of it shared with the sources. Major taxonomic groups such as Verrucomicrobia, Actinobacteria and Bacteroidetes showed higher aquatic affinities than Parcubacteria, Gammaproteobacteria, Alphaproteobacteria or Betaproteobacteria, which may be recruited and selected through different hydrographic habitats. A regional fingerprint was observed with lower alpha diversity and higher beta diversity in the central Pyrenees than in both ends. We suggest an ecological succession process, likely influenced by complex interactions of environmental source dispersal and environmental filtering along the mountain range geography.

中文翻译：

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高山湖泊区（西班牙比利牛斯）的区域社区集会驱动力和微生物环境因素，使浮游细菌形成。

自然生态系统中的微生物群落必须遵守严格的生态规则。对沿区域元社区的当地社区的研究可以揭示社区集会的模式，并解开潜在的生态过程。特别是，我们使用大型湖水资料集（> 300个湖泊）沿着比利牛斯山脉的地理，森林学和理化梯度，寻找区域规模的社区聚集驱动力。通过使用16S rRNA基因的高通量扩增子测序，并推断细菌移民的环境来源，我们表明表面水生细菌组合受到土壤，生物膜或沉积物的陆地种群的强烈影响，并主要通过pH碱度梯度进行选择。确实，来源比例解释了27％的社区差异，化学成分占总变化的15％，其中一半与来源共享。主要分类学类别（如疣状微生物，放线菌和拟杆菌）的水生亲和力高于可通过不同水文生境招募和选择的细小杆菌，γ-变形杆菌，α-变形杆菌或Beta变形杆菌。比利牛斯山脉中部比利牛斯山脉具有较低的α多样性和较高的β多样性的区域指纹。我们提出了一个生态演替过程，该过程可能受到沿山脉地理环境的环境源扩散和环境过滤的复杂相互作用的影响。可以通过不同的水文生境来招募和选择的丙种细菌，丙种细菌或乙种细菌。比利牛斯山脉中部比利牛斯山脉具有较低的α多样性和较高的β多样性的区域指纹。我们提出了一个生态演替过程，该过程可能受到沿山脉地理环境的环境源扩散和环境过滤的复杂相互作用的影响。可以通过不同的水文生境来招募和选择的丙种细菌，丙种细菌或乙种细菌。比利牛斯山脉中部比利牛斯山脉具有较低的α多样性和较高的β多样性的区域指纹。我们提出了一个生态演替过程，该过程可能受到沿山脉地理环境的环境源扩散和环境过滤的复杂相互作用的影响。