Relative influence of spatial over environmental and historical processes on the taxonomic and phylogenetic beta diversity of Neotropical phyllostomid bat assemblages

Aim: Environmental, spatial and historical dynamics are widely recognized as fundamental factors underlying community assembly along geographical gradients. We addressed the relative roles of these three processes on the taxonomic (TBD) and phylogenetic beta diversity (PBD) among 108 phyllostomid bat assemblages. Considering the bats' dispersal abilities, niche requirements and tropical origin, we hypothesized that the current environmental parameters would explain most of the taxonomic and phylogenetic variation among these communities. Location: Neotropics. Methods: We assessed taxonomic and phylogenetic similarities among these 108 communities using species compositional data. To disentangle the effects of different processes structuring these assemblages, we conducted variance partitioning using distance-based redundancy analyses. We also examined the spatial structure of these communities and used null models to test whether the assemblages are phylogenetically more or less dissimilar than would be expected by chance. Results: Most of the variation in TBD and PBD was accounted for by spatial processes. Spatial influences were consistent for beta diversity components and for groups of species with distinct geographical range sizes. We observed a strong and non-random spatial structure underlying the taxonomic and phylogenetic community composition. A pairwise comparison revealed that most communities had random variation with respect to phylogeny. Main conclusions: Spatial processes were more effective than environmental and historical processes in explaining species and lineages composition of 108 Neotropical phyllostomid assemblages, a result that could be due to topographic complexities limiting species dispersal in this region, regardless of the bats' dispersal capabilities. In contrast to previous studies of patterns of bat diversity at local and regional scales, our results suggest that the structure of bat assemblages is related to complementary ecological and evolutionary processes at different levels of diversity and geographical scales throughout the Neotropics.