Separating environmental and geographical determinants of phylogenetic community structure in Amazonian palms (Arecaceae)

Abstract

Phylogenetic information can provide important insight into the assembly of hyper-diverse tropical rainforest communities. The hierarchical nature and scale dependency of phylogenetic community structure can be used to disentangle complex networks of assembly mechanisms. Here, we outline how particular assembly mechanisms can be identified by analysing phylogenetic community structure on different scales related to space and environment. We present a case study on a large set of species-rich palm communities from the western Amazon basin. We aimed to elucidate the assembly of these communities by separating the roles of broad-scale biogeographic processes, habitat filtering and intra-habitat processes. Overall, we found phylogenetic clustering, which could be caused by a variety of different processes. When we reduced the species pool according to regions, habitats or soil sand content, we found that the structure was consistent with a combination of regional biogeographic differentiation, habitat filtering and within-habitat processes. The habitat filtering effect was strongest, although it varied in strength among communities in different habitats. Some phylogenetic structure could not be accounted for by biogeography or habitat, suggesting that intra-habitat processes such as micro-environmental filtering or biotic interactions also play a role.