Dispersal assembly of rain forest tree communities across the Amazon basin

We investigate patterns of historical assembly of tree communities across Amazonia using a newly developed phylogeny for the species-rich neotropical tree genus Inga. We compare our results with those for three other ecologically important, diverse and abundant Amazonian tree lineages, Swartzia, Protieae and Guatteria. Our analyses using phylogenetic diversity metrics demonstrate a clear lack of geographic phylogenetic structure and that local communities of Inga and regional communities of all four lineages are assembled by dispersal across Amazonia. The importance of dispersal in the biogeography of Inga and other tree genera in Amazonian and Guianan rain forests suggests that speciation is not driven by vicariance and that allopatric isolation, following dispersal, may be involved in the speciation process. A clear implication of these results is that over evolutionary timescales the metacommunity for any local or regional tree community in the Amazon is the entire Amazon basin.