Strong but opposing effects of climatic niche breadth and dispersal ability shape bat geographical range sizes across phylogenetic scales

Aim Climatic niche breadth and dispersal ability influence species distributions and are hypothesized as traits that determine variations in species range sizes. Here we test a hypothesis on the complementarity of their influences on species ranges in a phylogenetic framework and across phylogenetic scales. Location New World. Time period Cenozoic. Major taxa Leaf-nosed bats, Phyllostomidae. Methods We estimated phyllostomid range sizes from maps of species distributions. We used information on climate found within each species' range and a trait linked to flight performances to determine species climatic niche breadth and dispersal abilities, respectively. We used phylogenetic generalized least squares to test for the influence of climatic niche breadth and dispersal for the whole family, and phylogenetically weighted regressions to determine the influence of each variable at different phylogenetic scales, at the species level. Results Although both variables influence species ranges with a positive climatic niche breadth effect, we found an opposite and counterintuitive pattern for the effect of dispersal, as species with increased dispersal showed smaller ranges. By testing these variables effects for each species separately, our results showed an overall positive influence of climatic niche breadth, while for most species we did not observe an influence of dispersal, indicating phylogenetic non-stationarity considering the influence of dispersal ability on range size. Main conclusions We provide new insights on the determinants of species ranges, especially by challenging the traditional view that increased dispersal abilities translate into larger ranges. We highlight that idiosyncrasies during the evolution of major clades can play important roles in determining the influence of different processes in shaping species distributions, reflecting phylogenetic non-stationarity in range size dynamics. Further studies addressing these issues across phylogenetic scales will be essential in clarifying processes that underlie species ranges. As range size is correlated to extinction risk, such advances may provide crucial information on factors related to species' vulnerabilities.