Different species traits produce diverse spatial functional diversity patterns of amphibians

Trait selection is a critical step of functional diversity (FD) studies and is often hampered by the limited availability of trait data for large sets of species. Thus, most studies examine FD using traits determined primarily by the availability of data rather than a specific function. This practice implicitly assumes that the subset of functional traits available will be representative of the trait data of interest. Here, we test whether the different functional trait groups (FTGs-distinct axes of ecological niches of the species e.g. morphological, reproductive, physiological) show congruent FD spatial patterns and if one FTG could act as a surrogate for another FTG. We used data on the 85 amphibian species of Europe and 12 traits to estimate three aspects of FD (richness, evenness and dispersion) for three different FTGs (Morphological, Reproductive and Habitat-related) and the complete set of traits. Our results challenge the surrogacy value of one set of FTGs for another set of FTGs. We further found that this has an impact on identifying hotspots (different functions will have different hotspots). So the argument that FD is easier to preserve in less area due to the redundancy of traits may hold true for a specific function, but will not necessarily be the same for different functions. Finally, our results reveal that, for any given community, FD is not characterized by a single spatial pattern, but by many depending on the function analyzed.