Filogeografia em áreas abertas da América do Sul: origem e diversificação de linhagens de Scinax squalirostris (Anura, Hylidae)

• Autor(a) principal: Magalhães, Rafael Félix de
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/6085
• topic: Período terciário; Período quaternário; Campos; Pampas e chaco; Period tertiary; Period quaternary; Grassland; Pampas and chaco; CIENCIAS BIOLOGICAS::ECOLOGIA

(Phylogeography of Scinax squalirostris). In this work we used 175 individuals of Scinax squalirostris from 26 localities in the Brazilian states of Minas Gerais, São Paulo, Goiás, Mato Grosso do Sul, Santa Catarina, Rio Grande do Sul, Parana, and Distrito Federal, as well as individuals from Paraguay, Uruguay and Argentina. Three mitochondrial (cytb, 12S and CO1) and one nuclear (RAG-1) gene fragments were sequenced. The determination of the phylogenetic structured populations and the relationships among them were made under phylogenetic analyses based on Bayesian statistical methods. The most parsimonious relationship among haplotypes was made under the method of median-joining network. The delineation of the hypothetical operational taxonomic units was made under DNA mini-barcoding procedures, combined with genetic and phylogenetic evidence. In addition, we performed population structure tests of, gene flow and changes in population sizes. Finally, times of divergence among genealogical lineages were estimated by relaxed molecular clock procedures. Considering the phylogenetic species concept, there are two possible scenarios for the taxonomic lineages of the cryptic complex named Scinax squalirostris. In the first scenario, there are two possible species: one with tropical and other with subtropical/temperate distributions, respectively. The second scenario points to the existence of at least nine species: one in the Pampas, one in the Chaco and the remaining seven isolated in 'sky-islands' from the Cerrado and Atlantic Forest domains. The first cladogenetic event of the lineages dates from the Upper Miocene, approximately 7.5 million years ago. This may have occurred by the last contraction of Paranaense Sea. During this period, new suitable areas for S. squalirostris emerged, leading to the clades belonging to tropical and subtropical/temperate zones diversification, and it would be consistent with the first taxonomic scenario. The XI diversification within these two major clades occurred in the transition between the late Tertiary and early Quaternary. The current distribution of S. squalirostris in the tropical zone probably should be linked to climatic and geological changes that occurred in the transition between the Pliocene and Pleistocene. During the Quaternary glaciations, the grasslands have undergone expansion (periods during glaciations) and retraction (during interglacials). When the temperature and moisture increased in the Late Holocene, occurred retraction of the grasslands in favor to the expansion of forests and tree/shrub savannas. Thus, the suitable habitats to S. squalirostris were restricted to the grasslands at altitudes greater than 800m in the tropics. The cycles of grasslands isolation on islands must have influenced the recent diversification of the local clades of S. squalirostris.