Functional structure, taxonomic composition and the dominant assembly processes of soil prokaryotic community along an altitudinal gradient

As more attentions have been paid to microbial taxonomic community structure along altitudinal gradients, the knowledge of the altitudinal variations in microbial functional structure in terrestrial ecosystems is limited. More importantly, the dominant assembly processes that drive altitudinal variations in both taxonomic composition and functional structure remain unclear. To fill the gaps, we integrated soil prokaryotic taxonomic community structure, functional community structure and community assembly processes along an altitudinal gradient into a comprehensive understanding. The results revealed that both taxonomic community structure and core functional community structure of soil prokaryotic microbes significantly differed across altitudes. We detected the core functional groups associated with the redox reactions essential for microbial metabolism and biogeochemical cycles across altitudes. Chemoheterotrophy and photoautotrophy were dominant in abundance, indicating the important roles of primary energy metabolism for soil prokaryotic community. The whole prokaryotic community taxonomic composition was dominantly shaped by dispersal limitation (governing 74% of spatial turnover). The variation of functional structure was primarily caused by environmental selection, while the taxonomic variation within individual functional groups was weakly related to selection but mainly driven by drift. These results are critical for predicting the future dynamics of soil microbial community in the face of disturbances.