Biogeografia de Hylaeamys megacephalus (Rodentia Sigmodontinae): integração entre modelos de nicho ecológico e filogeografia

Abstract

Historical and ecological factors affect distribution and diversification of species. Hylaeamys megacephalus is a rodent from Amazonian forests and Cerrado, with distinctive lineages to the north and south of Amazonas River. Previous studies suggested allopatric divergence by the Amazonas River for northern Amazonia, and parapatric between southern Amazonia and Cerrado. We investigated the evolutionary history of the species integrating phylogeography and ecological niche models (ENMs). Through cytochrome b mitochondrial gene, we constructed a phylogenetic tree, haplotype network, estimating divergence time, historical demography, ancestor areas and dispersion and vicariance events. We ran ENMs of the species and its lineages, projecting it to the past. We analyzed niche similarity and habitat corridors. Our results show the three structured lineages, revealing sharing haplotypes only between south of the Amazon and Cerrado. All lineages diverged by vicariance in Pleistocene, however individuals with associated haplotypes diverged by dispersion and vicariance. We found low niche similarity between northern and southern Amazonia, but high between southern Amazonia and Cerrado. We corroborate vicariant diversification in northern Amazonia, associated with the establishment of Amazon river. However, due to the wide distribution of ancestral species, we suggest that environmental factors have also influenced this process, causing ecological variation between north and south of the Amazon before the rise of the barrier. About the lineages of the southern Amazon and Cerrado, previous studies have suggested diversification Parapatric, however, these lines showed high similarity ecological and model Parapatric Speciation requires selective variation. We suggest that these lineages diverged by the emergence of Xingu River, going through successive dispersion and vicariance events caused by change of the river’s water level during the Pleistocene.