Wind directionality and strength affects wetland invertebrate metacommunities in Patagonia

Abstract

Wind has the potential to shape metacommunities by affecting organism dispersal strength and directionality. Here we evaluate the relative importance of wind in the assembly of wetland invertebrate metacommunitiesof active (i.e. flying adults) and passive (e.g. through birds) dispersers in Patagonia. This region experiences some of the strongest winds on Earth, with persistenceof westerly winds. The study included invertebrate samples collected from 82 pristine wetlands across the Argentinian Patagonia. For each wetland we measured water quality, morphology and plant cover. These variables were used to calculate an environmental distance between sites (i.e. how each pair of sites wasin terms of local habitat conditions). Then, we built two metric of landscape resistance to dispersal between sites: topographic (i.e. least cost path between sites taking into account topographic barriers) and wind (i.e. least cost path between sites taking into account wind speed). We built distance-decay relationships of macroinvertebrate community similarity for each distance. Wind had amuch stronger effect than environmental conditions and topography on the metacommunity organization of passive dispersers. On the contrary, wind had a weak effect on the organization of active dispersers? metacommunities when compared with topography and environmental conditions. Our results suggest that metacommunity studies should account for the effects on external dispersal agents, with e.g. wind being a major determinant of community organization.