| Uncovering the mechanisms driving the diversity patterns across space and through time is of critical importance in microbial community ecology.Previous studies suggest that microorganisms also follow typical spatial scaling patterns as macro-organisms.However,it remains not clear whether different microbial functional groups differ in spatial scaling and how different ecological processes may contribute to such differences.In this study,two typical spatial scaling patterns,including taxa-area(TAR)and distance-decay relationships(DDR),were investigated for the whole prokaryotic community and seven microbial functional groups using marker genes including amoA-AOA,amoA-AOB,aprA,dsrB,mcrA,nifH and nirS.The analysis results are as follows:(1)Analysis of microbial community composition revealed that the dominant species for the whole prokaryotic community and most functional gene groups(aprA,dsrB,nifH,and nirS)were the Proteobacteria;the ammonia-oxidizing archaea(amoA-AOA)and ammonia-oxidizing bacteria(amoA-AOB)communities were dominated by the phylum Tharmarchaeata and Betaproteobacteria,respectively.The mcrA gene family were mainly carried by Euryarchaea taxa.In addition,it was found that the higher the diversity of the community,the lower the similarity of the community.Such results suggested that different microbial functional groups may harbor different diversity patterns and ecological processes across the sampling region.(2)Different microbial functional groups harbored different spatial scaling patterns.Microbial functional groups had weaker TAR slope coefficients than the whole prokaryotic community.The TAR of rare subcommunities is stronger than that of abundant subcommunities,which are generally not obvious.This suggested that rare subcommunities were mainly responsible for the TAR patterns,for both whole prokaryotic communities and different functional groups.The archaeal ammonia-oxidizing group,however,was found with stronger DDR pattern than the bacterial ammonia-oxidizing group.For both TAR and DDR,rare subcommunities were mainly responsible for the observed microbial spatial scaling patterns.(3)Significant association between environmental heterogeneity and spatial scaling metrics was observed for multiple microbial functional groups.Soil moisture content,salinity and water-soluble sulfate content were closely related to community structure.The similarity of microbial communities decreased with increasing geographical distance,while environmental heterogeneity increased with increasing geographical distance,indicating that microbial community construction was driven by a combination of spatial distance and environmental factors.In addition,a null model approach was employed to quantify the contribution of different community assembly processes in structuring the diversity and compositional variations of different microbial groups.Among them,dispersal limitation,which positively correlated with phylogenetic breadth,was also strongly associated with the strength of microbial spatial scaling.The results demonstrated that environmental heterogeneity and dispersal limitation simultaneously contributed to the microbial spatial scaling patterns.This study links microbial spatial scaling patterns with ecological processes,providing mechanistic insights into the typical diversity patterns followed by microbes. |
