Testando hipóteses de diversificação nas Florestas Neotropicais úmidas com base em anfíbios e répteis

Abstract

This work investigates how historical processes of landscape evolution in the Neotropical rainforests influenced patterns of genomic diversity and structure at interspecific, intraspecific, population, and comparative levels of the current diversity of amphibians and reptiles. For this purpose, we studied the diversification history of two broadly distributed taxa in Amazonia (AM), the lizard Gonatodes humeralis (Sphaerodactylidae) and the tree frogs species group Dendropsophus leucophyllatus (Hylidae), which also occurs in the Atlantic Forest (AF) of southeastern Brazil and Central America. To achieve the goals, I used New Generation Sequence approaches to obtain single nucleotide polymorphisms (SNPs) associated with restriction sites DNA sequencing (ddRADseq). In the first chapter, we worked with nine species of the D. leucophyllatus group to investigate and delimit the occurrence of possible new lineages and the origin and historical biogeography of the group, which was estimated to have started during Miocene at the AF, when historical connections between AF and western AM were possible by a south corridor. We obtained 14 independent lineages along the nine sampled species, which leaves no doubt about the group high cryptic diversity with a high potential of new species, mainly within the D. leucophyllatus-triangulum complex. Our findings also suggest that the Andes uplift could be responsible for environmental changes in the AM, which could be responsible for parapatric speciation by ecological adaptation. In the second chapter, we focus on the species D. elegans, which distribution is restricted to the AF, to carry out a genetic characterization and model-based approach estimating the divergence times of species populations along its latitudinal gradient. The results support the existence of three lineages corresponding to two populations geographically structured at the north and south distribution extremes with a contact zone between them possibly established after the Last Glacial Maximum. We conclude that climatic refugia during the Pleistocene were important for populational diversification in isolation and subsequent secondary contact and admixture between populations, generating the current spatial pattern of genomic diversity. Finally, in the third chapter we study the effects of the main Amazonian rivers in the populational structure and diversification of G. humeralis and D. leucophyllatus by using model-based phylogeographic analyses that take into account the presence/absence of migration events through the investigated barriers. Results indicate negligible migration rates across populations separated by main rivers (following the delimitation by Areas of Endemism), but divergence times recovered were very recent and differed between species, supporting a history of recent dispersion among rivers rather than a role as primary barriers for vicariant events.