Filter-dispersal assembly of lowland Neotropical rainforests across the Andes

Numerous Neotropical rainforest species are distributed in both Amazonia and Central America, reflecting a rich history of biotic interchange between regions. However, some plant lineages are endemic to one region, due in part to the dispersal barrier posed by the northern Andean cordilleras and adjacent savannas. To investigate the role of biogeographic filtering across the northern Andes in regional community assembly, we examined environmental tolerances, functional traits, and biogeographic distributions of >1000 woody plant species (trees, shrubs, lianas) locally co-occurring in forest plots in lowland Panama (542 species) and Amazonian Ecuador (667 species). High regional abundance was strongly predictive of the probability of being geographically widespread (i.e., present on both sides of the Andes). However, we also found that species with broad environmental tolerances (those that are able to inhabit high elevations and areas of low mean annual precipitation) were more likel...