Desvendando o desconhecido: diversidade, distribuição e diversificação de anuros no interflúvio Purus-Madeira

Abstract

The Purus-Madeira Interfluve (PMI) represents one of the less known areas of Brazilian Amazonia. Despite it is extremely threatened by anthropic actions, the knowledge about the taxonomic identity of anurans inhabiting the PMI and the processes driving their distribution and diversification are poorly known. The main goals of this thesis were to investigate the hidden diversity in anurans, provide bases to ecological and conservation studies through the description of new taxa, and illuminating the role of environment on species distribution and diversification along the PMI. In the first chapter, we integrated morphology, bioacoustics, and genetics to explore if there was hidden diversity in anurans of the genus Scinax along 1000 km of landscapes in the PMI. Integrative analyses revealed that approximately 82% of the regional richness in Scinax was unknown to science. Results highlighted how much the PMI faunal diversity is poorly known and its need for conservation actions. In the second chapter, we formally described the most widely distributed new species of Scinax in the PMI and tested if its geographic distribution and abundance were driven by environmental variables. Scinax ruberoculatus is easily distinguished from its congeners through morphological (adults and tadpoles) and bioacoustical characters. Differing from the predicted for aquatic breeding anurans, its distribution and abundance along the PMI is positively driven by silt content and not by forest structure (tree density). It is suggested that this habitat-association is driven by the species’ reproductive needs once reproductive sites in silty soils may be less ephemeral, favouring the survival of tadpoles of the new species. In the third chapter, we described a new species of Scinax with distribution apparently restricted to the central portion of PMI. Despite it is close related to species of the Scinax wandae clade, the new species is distinguished from all other Amazonian Scinax through morphology and colouration, as well as by the advertisement call. The species’ habitat is deeply threatened by the anthropic pressure due to property speculation as result of the reconstruction of the BR-319 highway. In the fourth chapter, Scinax onca was described based in specimens from two distinct populations in the PMI, one living in dense forests and the other in open forests. Phylogenetic analyses of the first chapter recovered these populations as reciprocally monophyletic. Differences in colour pattern, as well as its evolutionary relationship, led us to hypothesize that environmental gradients of the PMI may be responsible by observed differentiation in these populations. However, data collected along its distribution are necessary to elucidate if the observed differentiation is really influenced by environmental gradients. In the fifth chapter, we used a diminutive terrestrial anuran (Phyzelaphryne miriamae) and widely distributed in the PMI as a model to test if the gene flow along the landscape can be explained by the ecological gradient hypothesis. For the first time in Amazonia, genomic landscape analyses and thousands of single nucleotide polymorphisms (SNPs) were used to test this hypothesis. Genetic structure analyses estimated five ancestral populations in P. miriamae. Results indicated that the effect of environmental gradients on gene flow of the target species was pronounced. After accounting the effect of geographic distance, the explanation of environmental variables ranges from 24.7 % (silt content) to 30.2% (temperature seasonality). On the other hand, geographic distance explained just 2.3–3.7% of the gene flow. Although there is an effect of geographic distance on gene flow in P. miriamae, it is restricted to short and long distances, being null in moderated distances.