O papel da evolução de nichos na diversificação e potenciais impactos das alterações climáticas nas pererecas Neotropicais do gênero Pithecopus (ANURA: PHYLLOMEDUSIDAE)

Abstract

The ecological niche is an intrinsic trait of species that defines the specific requirements of individuals and expresses the set of conditions under which they can persist in nature, imposing limits on their distributions. Studies show that evolution towards conservatism or the divergence of past environmental preferences (niche) can have a profound influence on the evolutionary history of species, as well as on their responses to global climate change. The genus Pithecopus (Anura: Phyllomedusidae) is a group of 12 species of Neotropical charismatic tree frogs whose geographic distributions encompass a diverse mosaic of landscapes and environments, with such diversity and contrasting space occupation that may reflect the evolution of this trait to specific ecological requirements. In this thesis, I investigated how the ecological niche of Pithecopus species evolved, as well as the role of the evolutionary dynamics of this trait in the emergence of these species and genus diversification and how they will influence their responses to global climate change, accessing extinction risks in future climate scenarios. For this end, 243 occurrence records with high coverage of the known distribution of each of the Pithecopus were obtained and with these I built niche models and predictions of potential distributions. In the first chapter, I tested the presence of phylogenetic niche conservatism for different taxonomic levels (i.e., species and genus) using complementary analytical approaches, which estimate the patterns of overlap between the climatic niches of the species of the genus and verify the fit of position and width from this trait to models that describe different evolutionary scenarios. The results indicate that, in general, there is niche conservatism in Pithecopus. However, when different altitudinal environments were considered, species that occur in lowland regions present niches more similar to ancestral characteristics, while species distributed in mountainous complexes have more divergent niches. In the second chapter, using climate niche models and their projections into different future climate scenarios that incorporate the synergistic impacts of land use change models as dispersion filters, we investigate how Neotropical tree frogs of the genus Pithecopus will be impacted by climate change forecasts for the future, as well as evaluating the efficiency of protected areas in South America as valid conservation strategies. The results show that all Pithecopus species will be impacted by predicted climate change in the future. However, when considering species groupings in two clades occurring in different altitudinal environments, the results support the idea that the biodiversity associated with mountainous areas will be more incisively impacted by climate change since greater displacements and contractions were predicted for the distributions of these species in the future. Furthermore, the combination of species responses to changes in an environment largely transformed by constant human use of land with the insufficiency and inefficiency of protective measures for biodiversity will configure a threatening scenario for the survival of Pithecopus, especially for montane species. Finally, in the third and last chapter, I investigated the diversification of the Neotropical tree frog genus Pithecopus by evaluating the potential roles of geography and ecology as mechanisms of speciation. First, I evaluated the persistence of geographic and ecological signs of the cladogenetic process, recovering a significant association between patterns of range and niche with kinship. Then, I identified the most plausible scenario for the origin of these species by testing the congruence between distribution, ecological and phylogenetic patterns observed from of the data with the expected patterns under diversification scenarios commonly invoked to explain the origin of the Neotropical biota. The results show that non-significant associations between patterns of geographic and niche overlap with phylogenetic relationships indicate non-persistence of geographic and ecological signals in the diversification of Pithecopus. However, the congruence between observed geographic, ecological and phylogenetic patterns and expected patterns under scenarios that suggest both conservatism and rapid niche divergence, indicate that contrasting dynamics of niche evolution would be involved in the emergence of these tree frogs. Thus, my work demonstrates a prominent role of ecology in diversification within Pithecopus, a finding similar to those recently discovered for other tropical and neotropical taxa, while multiple patterns of niche evolutions emerged during the differentiation of these species.