Beta diversity of diatoms is driven by environmental heterogeneity, spatial extent and productivity

Simultaneous effects of productivity, environmental heterogeneity and spatial extent on beta diversity of microbial communities have seldom been investigated. Here, we evaluated how these components are related to diatom beta diversity in tropical reservoirs. We hypothesised positive relationships between diatom beta diversity and environmental heterogeneity, productivity and spatial extent. Regression models were used to model beta diversity as a function of different measures of abiotic environmental heterogeneity, productivity, reservoir morphology, spatial extent, and habitat heterogeneity. Our results suggest a strong relationship between beta diversity and environmental heterogeneity, productivity and spatial extent. However, contrary to our hypothesis, productivity was negatively related to beta diversity. We speculate that artificial eutrophication can lead to decreased beta diversity (biotic homogenisation). Furthermore, the relationship between beta diversity and abiotic environmental heterogeneity depends how this component was measured. In conclusion, environmental heterogeneity and dispersal limitation were likely the main factors that determined diatom beta diversity in tropical reservoirs.