Diversificação do complexo Allobates femoralis (Anura, Dendrobatidae) em florestas da Amazônia brasileira: desvendando padrões atuais e históricos.

Abstract

In this study, I analyze aspects of the diversity and evolution of a group of phylogenetically related anuran species, which are widely distributed along the Amazon basin, and which have been historically recognized as belonging to a single taxon: Allobates femoralis. The first chapter addresses the systematic relationships between several allopatric populations of this group and formalizes the recognition and description of a new species: Allobates hodli. It also highlights the occurrence of additional monophyletic lineages, which present particular acoustic and morphological phenotypes, and are indicated as potential cryptic species. In the second chapter, I evaluate the effect of the Madeira River on the genetic, morphological, and acoustic differentiation between A. femoralis populations distributed along both interfluves, applying phylogeographic analyses in order to verify the congruence between observed differentiation patterns and those expected if the Madeira River has functioned as a vicariant barrier since its origin. Phylogenetic and population analyses based on mitochondrial molecular markers suggests patterns that are coincident with the hypothesis that the Madeira River channel represents a historical barrier causing the isolation between populations from opposite riverbanks. However, the effectiveness of the river as a vicariant barrier is variable along its course, and possible events of dispersal between riverbanks are reported for localities between its middle and upper course. Morphology and calls of populations sampled on the same interfluve are not more similar to each other in when compared to populations sampled on the opposite riverbank, suggesting that differentiation of phenotypic characters is influenced by additional evolutionary mechanisms. In the third chapter, I present the genetic characterization of a contact zone between A. femoralis and A. hodli, located on the upper Madeira River. Analyses of mitochondrial and microsatellite molecular markers suggest that natural hybridization between the two species is more frequent along the geographic central line of the contact zone, decaying abruptly less than two kilometers downstream and upstream of this area. Genetic diversity estimates measured at sites adjacent to the contact zone support the existence of selection against hybrids originating from direct crosses between parental individuals belonging to the two species.