LAUSR

Dispersal is one of the main determinants of metacommunity assembly, yet its interaction with the landscape network structure has not been fully elucidated. Large-scale regional factors such as the centrality–isolation gradient influence community abundance and richness, but small-scale regional factors, such as the direction or the distance among water bodies, might also influence them. Furthermore, the specific dispersal ability of each of the taxa will also determine this interaction. All these drivers are generally difficult to analyse together, but mesocosms usage combined with network analysis can help disentangle their relevance. We used these approaches to analyse how large and small regional factors influence dispersal dynamics. We set up several mesocosms around two source ponds with divergent locations within the network centrality–isolation gradient, at different distances and in different directions. We analysed macroinvertebrates composition and temporal trends throughout the hydroperiod considering the two regional factors: large (centrality–isolation gradient) and small (distance or direction separately) and dispersal ability (i.e. weak or strong). The large scale, being central or isolated, determined abundance and richness across the hydroperiod, with greater values in central locations. However, small regional factors, especially direction, modulated this trend making it similar to the central locations. Contrastingly, the small regional scales did not affect community composition, which differed along the large scale. Our results suggest that centrality–isolation plays a marked role in assembly processes favouring greater dispersal in central locations. However, this general pattern can be modulated by smaller regional factors and by intrinsic taxa dispersal ability, something that must be accounted within the metacommunity framework.