História evolutiva dos lagartos anões (Lygodactylus, Gekkonidae) no continente Sul Americano

Abstract

Which processes and mechanisms are responsible for species diversification? This old question has been revolutionized with technological, computational and methodological advancements, and is now being understood in a way that was previously not possible. Phylogeography is a multidiscipline that uses tools derived from biogeography, molecular phylogeny, and population genetics to understand the context of gene distribution in time and space. The present study uses phylogenetic and phylogeographic analyses to infer determinant processes in the diversification of the lizard genus Lygodactylus in Seasonally Dry Tropical Forests (SDTF) in South America. In the first chapter we investigate the relationships among South American Lygodactylus species, seeking to understand the influence of the Pleistocenic Arc on its diversification and whether these species represent a monophyletic group. Through phylogenetics and species delimitation analyses we recovered the monophyly of the group in relation to African species and recognized L. klugei as a cryptic species complex. We suggest that Lygodactylus in South America actually comprises five species instead of two. The divergence time among L. klugei and candidate species endemic to SDTFs was not congruent with the Pleistocenic Arc Hypothesis. However, we suggest that the fragmentation of SDTFs likely influenced the divergence of L. wetzeli, and of a candidate species endemic to a SDTF enclave within the Cerrado biome (São Domingos, Vale do Paranã region). In the second chapter we investigate the diversification within the Caatinga, testing the role of the São Francisco River (SFR) as a prominent geographic barrier. We used a lizard endemic to this region (L. klugei) as study model. We delimited the existent lineages, investigated the genetic relationships between them, the spatio-temporal diffusion history, and used a migration analysis to test the riverine hypothesis (barrier to gene flow). We recovered two lineages structured in respect to the SFR: a northern and a southern one. Lineage divergence occurred 295 kya, congruent with the course change of the SFR to its current position. We found no influence of the paleo-SFR on L. klugei structure.