Climatic niche and its evolutionary rates are associated to reproductive modes in treefrogs (Amphibia: Anura: Arboranae)

Frog species that have terrestrial reproductive modes are thought to be confined to areas with higher temperature and humidity while species that breed in water are not. From an evolutionary perspective, we investigated whether the differences in the climatic niches of treefrogs are associated with differences in reproductive modes, which define their dependency on water for reproduction. We predict that species that do not depend exclusively on water for reproduction have conserved climatic niches. We used published data on reproductive modes to classify the level of water dependency for reproduction (0=eggs and tadpoles in water; 1= eggs out of water and tadpoles completing development in water; 2= eggs and tadpoles placed outside water; 3= plastic phenotype). We characterized the position of climatic niches of treefrogs based on the environmental conditions comprised by their occurrence points using a multivariate index (OMI analysis). Geographic and environmental data were obtained from the GBIF, VertNet, SpeciesLink and WorldClim databases, respectively. We modeled correlated evolution of species’ niche position and reproductive modes under Brownian motion considering single and multiple evolutionary rates. This framework resulted in four different models from which we selected the one that best described our data (the model that showed the lowest AICc value). Our results showed that the reproduction mode influenced climatic niche differences among species. Climatic niches of species that totally depend on water bodies for reproduction evolved faster (σ0= 1.04286493) when compared to those of species that do not totally depend on water bodies (σ1= 0.46118030; σ2= 0.65941597; σ3= 0.47796361). Thus, treefrogs with terrestrial reproduction showed climatic niche conservatism that, in turn, suggests that these species may not be able to disperse into new habitats. Conversely, treefrogs with aquatic reproduction showed climatic niche lability, when compared to species less dependent on water, suggesting a potential for geographic expansion.