Análises moleculares em Xenarthra: contribuições para a sistemática filogenética de Tolypeutinae, taxonomia de Cabassous e filogeografia de Bradypus torquatus.

Abstract

The Magnaordem Xenarthra comprises the orders Pilosa (anteaters and sloths) and Cingulata (armadillos). They are distributed from Mexico to the south of South America with the exception of Dasypus novemcinctus that has its distribution extended to the United States. Despite the understanding of some systematic and taxonomic aspects of Xenarthra, few studies have been totally focused on their subfamilies or within a particular species. The subfamily Tolypeutinae is composed of the genera Cabassous, Priodontes and Tolypeutes and, since the description of its species, its systematics has several changes and there is not yet a consensus between morphological and molecular works about the phylogeny within this subfamily. Cabassous is the genus of most species of family Tolypeutinae composed of four species: Cabassous centralis; Cabassous chacoensis; Cabassous tatouay and; Cabassous unicinctus, the latter divided into two subspecies, C. u. unicinctus and C. u. squamicaudis, that there are still many doubts as to its taxonomic classification. Bradypus torquatus, also known as "Maned sloth" is an exclusively Brazilian species and suffers considerably the effects of the reduction of its habitat. To date, there have been three main studies on the phylogeography of B. torquatus where all showed high level of genetic structure in the sampled regions and isolation among the studied populations. However, these analyzes were done using only mitochondrial markers (mtDNA) that represent only the matriarchal history of their lineages which may not effectively reconstruct the demographic history of the species. In order to increase the knowledge about xenarthrans genetics, three studies were carried out. The first one is a bibliographical review of the Tolypeutinae systematics and the proposal of a new phylogeny due to the relationship between Cabassous species different from that currently proposed by other authors. In the second work, with molecular markers, analyzes of species delimitation in Cabassous was performed and our results corroborate the hypothesis that Cabassous unicinctus squamicaudis and Cabassous unicinctus unicinctus are two species. Furthermore, we suggesting new studies to understand the relations between C. u. unicinctus and C. centralis. Finally, in the third work, another study using nuclear and mitochondrial molecular markers of B. torquatus with time scaled phylogeography and population inferences was performed and a high level of structuring between the analyzed populations was evidenced and its phylogeographic reconstruction refers to a dispersion pattern directed by events occurring in the Pliocene and Pleistocene. Besides, we propose a new geographic region for the ancestral lineage of this species.