Evolutionary patterns of range size, abundance and species richness in Amazonian trees
Amazonian tree species vary enormously in their total abundance and range size, while Amazonian tree genera vary greatly in species richness. Here, we construct a phylogenetic hypothesis that represents half of Amazonian tree genera in order to analyse evolutionary patterns of range size, abundance, and species richness. We find several clear, broad-scale patterns. Firstly, there is significant phylogenetic signal for all three characteristics, i.e. closely related genera tend to have similar numbers of species and similar mean range size and abundance. Additionally, the species richness of genera shows a significant, negative relationship with the mean range size and abundance of their constituent species, while mean range size and abundance are significantly, positively correlated. These correlations are stronger in the raw data, but still significant when using phylogenetically independent contrasts. We suggest that tree stature and/or other phylogenetically related biological traits underlie these results. Lineages comprised of small-statured trees show greater species richness and smaller range sizes and abundances. Lastly, the phylogenetic signal that we evidence for range size suggests that should many small ranged species go extinct, greater phylogenetic diversity may be lost than expected if range size were distributed randomly across the phylogeny.