Variação morfológica e genética em populações de Marmosops incanus (Lund, 1840) (Didelphimorphia, Didelphidae)

Abstract

Marmosops incanus is a brazilian endemic didelphid occurring in eastern Brazil, from Sergipe to São Paulo, to the interior of Minas Gerais and Bahia, in Atlantic Forest, Cerrado and Caatinga areas. In this study, at first, it was carried out a literature review to check its status quo, discussing taxonomic history, systematics and morphological, genetic, conservationist, ecological, life history and geographic distribution aspects. Finally, knowledge gaps and suggested perspectives for advancing studies in M. incanus are presented. Something that is not exactly a hiatus, but deserves more attention, is related to the morphological and genetic diversity in the species in previous studies with limitations on the geographical and numerical coverage of the sampling. In these studies the species has great molecular variation that does not match the morphological diversity. Therefore, in a second moment, I had the goal of deepening the investigation of the morphological and genetic diversity in M. incanus throughout its area of occurrence and with a wide sampling of localities and individuals, evaluating whether there is congruence between possible patterns in the new results and comparing them to the literature, to better delineate the structure of the variation in this species. I performed: 1) Phylogeographic analysis with the mitochondrial cytochrome b gene, obtaining phylogenetic trees by different methods (Maximum Parsimony, UPGMA and Maximum Likelihood) and genetic distances between the main formed clades; 2) Morphological analysis of cranial, appendicular skeleton and external characters; 3) Morphometric univariate (Analysis of Variance) and multivariate (Principal Component Analysis), and descriptive analysis of craniodental and external body dimensions measurements. The results constitute solid evidence that it is a taxon with relevant genetic and morphological variation, mainly in more southern groups in relation to the more northern (specially the mountain and south groups of Rio de Janeiro). The species shows strong morphometric variation along its distribution, which is reflected in phylogeography with striking discontinuities and geographically structured populations. This diversity found in M. incanus must also be taken into account for its conservation, with the purpose of protecting and maintaining the morphological and, mainly, genetic legacy. However, in spite of these results, I suggest that M. incanus continue to be treated as a single valid species and that, in a cautious way, taking care for achieving the best possible information to make conclusions about cryptic species enclosed in this taxon, I recommend a more in-depth research on issues that deserve greater attention. I present some future perspectives of study (some already underway) to provide new evidences at the molecular and morphometric level, under new methodological perspectives (Microsatellite Markers, and Canonic Variable Analysis, Discriminant Analysis and Geometric Morphometrics, respectively) and some new approaches on other aspects (Modeling of Species Distribution)