Distinct ecological mechanisms drive the spatial scaling of abundant and rare microbial taxa in a coastal sediment

AimRevealing the ecological mechanisms driving the diversity patterns of microbial communities across space and through time is an essential issue in microbial biogeography. This study links microbial spatial scaling with ecological mechanisms, aiming to provide novel mechanistic insights into the biogeographic patterns followed by different types of microbes. LocationBeibu Gulf, a semi-enclosed oceanic bay located on the southern coast of China. TaxonBacteria, which were further classified as abundant and rare taxa. MethodsBy employing high throughput sequencing, two typical spatial scaling models, diversity-area (DAR) and distance-decay relationships (DDR), were investigated for the abundant and rare microbial communities in a coastal sediment ecosystem. Both alpha- and beta-diversity indices were extended to Hill numbers to verify the contribution of abundant and rare taxa to DAR and DDR. The iCAMP approach was used to quantify the contribution of different ecological processes in structuring microbial communities. ResultsStrong spatial scaling patterns were observed for the whole communities and the rare subcommunities but only weak patterns for the abundant subcommunities. Rare subcommunities were mainly responsible for the observed spatial scaling patterns, as confirmed by extending spatial scaling diversity metrics to Hill numbers. Both environmental heterogeneity and local community assembly mechanisms drove the spatial scaling of microbial communities. Strong ecological drift and dispersal limitation underlay the spatial scaling of rare subcommunities, whereas high homogeneous selection weakened the spatial scaling of abundant subcommunities. Main ConclusionsRare taxa were mainly responsible for the biogeographic patterns followed by sediment microbial communities in the Beibu Gulf. Distinct ecological mechanisms underlay the different biogeographic patterns followed by abundant and rare subcommunities.