Disentangling the role of niche-based and spatial processes on anuran beta diversity in temporary ponds along a forest–grassland transition

Abstract

Evaluating beta diversity patterns along environmental gradients and different geographic ranges helps comprehend the roles of niche-based and spatial processes to metacommunity structure. Pond-breeding anuran composition depends on environmental predictors such as climate, vegetation type and habitat features as well as spatial processes (e.g., dispersal limitation or distances among patches). Here, we investigated the role of spatial and local (water chemistry and habitat structure) and regional (climate) environmental predictors to tadpole beta diversity (and its turnover and nestedness-resultant components) in temporary ponds distributed along a forest–grassland transition in the southern Brazilian Coastal Plain. Additionally, we investigated the role of the assessed predictors within forest and grassland sub-regions to test for congruence in their contribution across vegetation types. Turnover was the most relevant component of beta diversity. Spatial predictors alone explained beta diversity (and both components) at the broadest scale. However, the contribution of environmental and spatial predictors to beta diversity differed between sub-regions. Spatial and local environmental predictors independently explained beta diversity in the grassland, while in the forest sub-region, local predictors and spatially-structured climate were the most important. Our results revealed a complex interplay of niche-based and spatial assembly processes shaping anuran metacommunities. The different relationships of environmental and spatial predictors with beta diversity in the forest and grassland sub-regions suggest that the contribution of assembly processes to anuran metacommunity structure change with vegetation type.