Drivers of beta diversity of Odonata along a forest-grassland transition in southern Brazilian coastal ponds

Assessment of beta diversity patterns in relation to environmental and spatial drivers can provide useful insights into the underlying mechanisms structuring communities (deterministic and dispersal limitation). However, the relative importance of each mechanism and driver beta diversity patterns in freshwater communities is assumed to change with ecosystem type, scale of observation, and among groups with different dispersal abilities. We assessed beta diversity patterns of assemblages of odonate larvae in relation to geographical distances and scale-specific environmental drivers in southern Brazilian coastal ponds along a latitudinal gradient. We expected to find similar contributions of deterministic and dispersal limitation mechanisms to odonate assemblages and distinct patterns of beta diversity between suborders Anisoptera and Zygoptera. We found low values of beta diversity (probably related to distribution of generalist taxa and environmental conditions constituted by temporary ponds). Mantel and partial Mantel tests detected distinct relationships between dissimilarity in scale-specific drivers and geographical distances with beta diversity of Odonata. Zygoptera was influenced by dissimilarity in local- (presence of riparian vegetation and connectivity) and regional-level (climate) variables, whereas Anisoptera was influenced by geographical distances. Our results supported our hypothesis that changes in the composition of assemblages of odonate larvae in temporary ponds were jointly driven by deterministic and dispersal limitation mechanisms. Furthermore, the similar contributions of nestedness and replacement components and the differing responses of Anisoptera and Zygoptera to local- and regional-level environmental drivers and geographical distances indicate that the relative importance of environmental and spatial drivers to beta diversity patterns in ponds is scale-specific.