Dispersal traits drive the phylogenetic distance decay of similarity in Neotropical stream metacommunities

Abstract

Aim: The drivers of phylogenetic beta diversity include both local processes (e.g. environmental filtering) and regional processes (e.g. dispersal limitation). The role of environmental filtering can be investigated more directly by analysing community-environment associations, but dispersal limitation is one of the most challenging processes to examine. We investigated the role of traits related to dispersal - flight capacity, body size and voltinism - as drivers of phylogenetic distance decay relationships in Neotropical stream insect communities. Location: Headwater streams spread over 600 km in south-eastern Brazil. Methods: We compiled a data set of aquatic insect communities inhabiting streams across the State of São Paulo (Brazil). Then, we investigated environmental and spatial signals on phylobetadiversity patterns of aquatic insects using Mantel tests, multiple regressions on distance matrices and variation partitioning. We employed null models to investigate whether phylogenetic distance decay differed from pure compositional distance decay. We deconstructed the data set based on dispersal-related traits; we then ran distance decay analyses for these subsets separately. Results: Geographical distance, rather than environmental distance, better explained the patterns of phylobetadiversity. We found that the phylogenetic decay relationship differed from the relationship expected for the null models only for univoltine, large-bodied genera with a high-flight capacity. Main conclusions: Dispersal limitation, rather than species sorting, was the main driver for phylogenetic beta diversity in the metacommunity that we studied. We suggest that life-history strategies and mainly voltinism drive the distance decay of similarity in the insect communities examined. We additionally discuss the role of dispersal events over time to explain differences in distance decay patterns among tropical and other regions.