Spatial distance explains the periphyton metacommunity structure of a neotropical stream network

Environmental and dispersal drivers are determinants of periphyton metacommunities. However, the effects of these predictors can vary according to the facet of biodiversity assessed. In this study, we assessed the relative importance of local environment (i.e., limnological variables), regional landscape (i.e., land use), and spatial distance (i.e., overland and watercourse dispersal routes) components for the periphytic community in 30 Cerrado stream sites. For this, we estimated different metrics, such as the total density, beta diversity, local contribution to beta diversity (LCBD), species richness, and composition. This last metric was obtained considering the complete and deconstructed communities according to the type of adhesion to the substrate. We found 128 species with a predominance of the Bacillariophyceae, of which most have loosely adherence to the substrate. The algae community showed a high turnover of species along the hydrographic drainage. Besides, spatial distances were significant for species richness, total density, and species composition metrics using overland or watercourse distances. The spatial distance was also crucial for species composition tightly adhered to the substrate. Nevertheless, any community metric had no local environment and regional landscape effects. Therefore, on a large spatial scale, the effect of the spatial component can be attributed to species dispersion limitation, whereas on a finer spatial scale, mass effect was the primary process driving the variation among communities. In this sense, while for some species dispersal is limited by higher distances, for others dispersing to streams with suboptimal conditions can be associated with physiological aptitudes and high reproductive rates, which allow for the maintenance of species in the studied stream sites.