Different elevational environments dictate contrasting patterns of niche evolution in Neotropical Pithecopus treefrog species

Abstract

Understanding how species' ecological niches evolve can shed light on observed large-scale biogeographic patterns, temporal range shifts, and the potential ability for species to cope with climate changes. Here, we investigated climatic niche evolution in the Neotropical treefrog genus Pithecopus by testing for phylogenetic niche conservatism (PNC). We first evaluated niche overlap patterns based on pairwise niche comparisons of sister species pairs inferred from two alternative topologies for the genus, where higher niche overlap for those pairs compared to random species pairs would represent evidence of PNC. Second, we evaluated phylogenetic conservatism of climatic niches by fitting evolutionary models for niche position and niche breadth across the two alternative phylogenetic trees for the genus. Sister species pairs did not show higher mean niche overlap when compared to random pairs. Comparisons considering species' elevational habitats, on the other hand, showed that lowland sister species had greater niche overlap and montane species lower overlap than expected given the prevailing environmental conditions in each habitat, suggesting different evolutionary histories of niche differentiation for species with different elevational ranges. The best fit of niche position and breadth to both stasis and drift models supported the existence of PNC. We conclude that evolution of climatic niches in Pithecopus suggests overall PNC and that the contrasting patterns found for lowland and mountainous species reinforce the importance of considering the effects of habitat type in understanding climatic niches dynamics. Abstract in Portuguese is available with online material.