Cytogenetic, molecular phylogeny and phylogeography on Phyllomedusa genus (Anura, Hylidae)

We conducted cytogenetic, phylogenetic and phylogeographical studies to investigate aspects of chromosomal and molecular evolution in the Neotropical tree frogs of the genus Phyllomedusa genus (Hylidae, Phyllomedusinae), which have been the subject of extensive taxonomical debate. In the first chapter, the study focuses on the morphological variation found in populations attributed to P. hypochondrialis, and examines whether this variation is interspecific or inter-population. The results of this analysis support the need for a thorough revision of the phenotypic features used to discriminate P. azurea and P. hypochondrialis, given the considerable overlap found in these characters when more populations are samples. We also report inter- and intra-population variability in the NOR of P. hypochondrialis. In the second chapter, we use phylogeographic approaches to evaluate the source of the karyotype variation found within P. hypochondrialis, provide a better delimitation of the Brazilian populations of P. azurea, and estimate the genetic diversity within P. nordestina. These three species are closely related, but are associated with distinct South American morphoclimatic domains. Our results reveal a deep genetic structuring in the P. hypochondrialis populations, based four well-supported clades with a low migration signal among haplogroups. The evolutionary history of this species has been influenced by the interaction between the geomorphological changes occurring in the Miocene-Pliocene that have persisted through the episodes of climatic fluctuation that occurred during the Pleistocene. The populations of the Cerrado domain appear to have colonized this region during the Pleistocene period, when successive cycles of forest expansion and retraction may have facilitated expansion into this biome via gallery forests. We were able to recognize two cryptic lineages within the P. nordestina populations, differentiated by the São Francisco River in northeastern of Brazil. Estimates of coalescence time indicated a process of divergence between two geographic clades of P. nordestina during the Pliocene-Pleistocene transition, which is temporally congruent with historical modifications to the course of the São Francisco River. This geographic barrier has had a primary role in the divergence of lineages, supported by the high differentiation between populations from opposite margins of the river and the absence of gene flow between haploclades. A strong signature of genetic decline marks the evolutionary history of the Brazilians populations of P. azurea. While more extensive surveys are needed, Brazilian populations of this species appear to be restricted to the Pantanal biome. In the third chapter, we describe a new species of the P. hypochondrialis group, diagnosed using molecular, morphological and chromosomal approaches. The new species is closely related phylogenetically with all the highland species of the clade, revealing an interesting biogeographical pattern. Finally, in chapters four and five, we present cytogenetic data on four species of the genus Phyllomedusa (P. vaillantii, P. tarsius, P. distincta, P. bahiana and P. ayeaye). We found conservative karyotypes, permitting the recognition of chromosomal homologies. Despite the gaps in the chromosomal studies of this genus, the inter- and intraspecific variation found in the number and location of rDNA sites reflects the rapid rate of evolution of this character in Phyllomedusa, and highlights the important role of this sequence in the chromosomal evolution of this genus (AU)