Deconstructing species richness–environment relationships in Neotropical lianas

Abstract

Aim: Studying species richness patterns by considering all species as equivalent units may prevent a deeper understanding of the origin and maintenance of biodiversity. Here, we deconstructed the species richness of Neotropical lianas by specific attrib-utes of species to study richness–environment relationships.Location: Neotropics.Ta xo n: Tribe Bignonieae (Bignoniaceae), the largest clade of Neotropical lianas.Methods: We used five morphological, one geographical and two evolutionary at-tributes of species, each with 2–7 attribute states. We compared the environmen-tal response of species richness of each attribute state to the response of overall Bignonieae species richness. For those groups of species that differed in their envi-ronmental response to three-dimensional habitat structure, climate and soil we as-sessed: (a) the magnitude and direction of the environmental response; and (b) the variation in species richness explained by environmental variables and spatial filters using variation partitioning analysis.Results: We identified eight attribute states whose richness–environment relation-ship differed from the overall richness pattern: three morphological (species with shrubby habit, lacking tendrils and with seeds bearing ellipsoid wings), three geo-graphical (species with small, small-to-medium and medium-to-large range sizes) and two evolutionary (species of the genera Amphilophium and Cuspidaria) attribute states. Areas with high species richness of these eight attribute states did not overlap with the centres of Neotropical diversity in the tribe Bignonieae. A high fraction of the variation in species richness of these eight attribute states was accounted for by spatial filters or remained unexplained.Main conclusions: The richness deconstruction approach revealed that richness–environment relationships of species with specific attribute states differ from the overall species richness pattern. These morphological, geographical and evolutionary attribute states are mostly related to the survival and persistence in savanna habi-tats, and show that ecological strategies and evolutionary histories need to be taken into account to fully understand richness–environment relationships.