Date of Award
Ph.D. in Biological Science
Aim: Reveal the evolutionary processes that contributed to biotic diversification in the Cerrado savanna using amphibians as a model. Evolutionary patterns were investigated by comparing the phylogeographic and biogeographic history of biome-specific yet widely distributed amphibian species (Chiasmocleis albopunctata, Dendropsophus rubicundulus and Physalaemus nattereri). Location: Cerrado region, central South America. Methods: I sampled thousands of loci randomly distributed throughout the genomes of all three species. I applied phylogenetic, phylogeographic, demographic, and coalescent species delimitation methods to these molecular data, in combination with species distribution modeling for the past, in order to resolve questions of evolutionary history, taxonomic diversity, species boundaries, and test hypotheses that implicate climatic (stable/unstable) and geomorphological events (plateau/valley) in the formation of this diversity. Results: The C. albopuntata species group is distributed in the Bolivian and Brazilian savannas and Chaco and it is comprised of at least tree species C. albopunctata, C. mehelyi, and a composite lineage that includes: C. bicegoi, C. centralis, and C. sp. The Cerrado species C. centralis, D. rubicundulus and P. nattereri were each found to have three distinct, genetic populations widely distributed in the Neotropical savannas. No patterns of genetic differentiation related to geomorphology (plateau vs. valley populations) nor climatic stability in any of the species was observed. The demographic models indicate the presence of migration between populations, demonstrating that there are no important geographic barriers to gene flow. Conclusions: The results highlight the likely influence of the Atlantic Forest as the source for C. albopunctata species group inhabiting the dry open areas of the Neotropical savannas. The further uplift of the Brazilian shield during the Pliocene and Pleistocene was an important event for diversification of C. centralis, D. rubicundulus and P. nattereri, and the isolation by distance also promoted the differentiation among the populations of C. centralis, D. rubicundulus and P. nattereri, in combination with the climatic fluctuations during the Quaternary.
da Costa Arantes, Ísis, "Looking into the Past: The Diversification of Amphibians in the Neotropical Savannas" (2019). Electronic Theses and Dissertations. 1567.