Access the paper here. Biodiversity affects ecosystem function through species’ functional traits. Although it is possible to predict species richness (SR) patterns along environmental gradients, whether functional diversity (FD) changes in predictable ways is not known. In arid environments, SR typically increases with rainfall. Aridity may limit functional differentiation by allowing only certain traits, but could also be associated with diverse traits associated with various strategies for coping with spatial and temporal variation in resources. Rare species may …