Large- and small-regional-scale variables interact in the dispersal patterns of aquatic macroinvertebrates from temporary ponds

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.