Role of environmental, historical and spatial processes in the structure of Neotropical primate communities: Contrasting taxonomic and phylogenetic perspectives

To evaluate relative importance of niche, historical and spatial processes on the taxonomic and phylogenetic structure of primate communities. Location: Neotropics. Methods: Data on community composition for 74 sites were gathered from the literature. Communities were characterized based on taxonomic and phylogenetic composition. Three predictive matrices were used as explanatory variables representing ecological (environmental), historical (riverine barriers and Pleistocene refugia) and dispersal-based spatial hypotheses (spatial principal coordinates of neighbour matrices vectors based on geographic coordinates). Variation partitioning analyses were used to decouple independent and shared effects. Permutation procedures based on redundancy analysis were used to determine if explained variation was statistically significant. Results: Forty-nine per cent of variation in taxonomic structure and 66% of variation in phylogenetic structure was explained by selected predictor variables. Independent effects of spatial variables explained the largest portion of variation in both diversity metrics. Fractions representing shared effects of historical and spatial variables, and of all variables combined, were also large and significant. Independent effects of environmental and historical variables were small to non-existent (<4%). When analysing each phylogenetic metric independently the relative contributions of shared fractions changed, although the independent spatial fraction remained the most important predictor. Main conclusions: Our results show that purely spatial processes, such as dispersal limitation, may play a stronger role in structuring primate communities than niche mechanisms and historical events. Furthermore, we find that the influence of ecological and evolutionary mechanisms is conflated with spatial processes, suggesting that community structure is determined jointly by spatial mechanisms reflecting environmental gradients and biogeographical processes. Although the relative contributions of each predictor variable were similar between taxonomic and phylogenetic metrics, a deeper examination of phylogenetic metrics suggests that ecological, historical and spatial mechanisms interact in complex ways to determine current patterns of phylogenetic community structure.