Dimensions of amphibian alpha diversity in the New World

Aim The links between taxonomic, functional, and phylogenetic diversity and how these vary geographically are key to understanding how historical and contemporary processes have shaped communities at regional and local scales. Here, we evaluate the links between taxonomic, functional and phylogenetic diversity for the amphibians in the Continental Americas and how these vary geographically under an explicit hypothesis testing framework. Location Continental Americas. Taxon Amphibia. Methods We identify spatial disparities between biodiversity dimensions (taxonomic, functional and phylogenetic) using geographically weighted regressions. Based on these mismatches we examined whether different eco‐evolutionary processes would fit (competitive exclusion, habitat filtering, available ecological space, strong biotic interactions, speciation rates, and dispersion). Results We found extensive variation in spatial mismatches between the three dimensions of biodiversity examined here. In general, at higher latitudes, we detected relatively little phylogenetic diversity, suggesting rapid functional diversification from temperate clades. In contrast, at low latitudes, environmental filtering mechanisms appear to be restricting functional diversity. Main conclusions The geographical mismatches between dimensions of diversity suggest different eco‐evolutionary causes. Patterns of diversification across amphibian lineages demonstrate how different environments can have contrasting effects on the different dimensions of diversity, potentially leading to decoupling. Neither dimension of alpha diversity of amphibians is a general predictor for another, and thus, general explanations for amphibian diversity and evolution should be avoided. Nonetheless, these dimensions can provide critical insights about conservation measures that explicitly emphasize evolutionary history, functionality or classic species richness.