Límites de especies y relaciones filogenéticas dentro del género Necromys (Cricetidae, Sigmodontinae, Akodontini): evidencia molecular

D'ELÍA, G.; PARDIÑAS, U.F.J.; SALAZAR-BRAVO, J.; JAYAT, P.

Praia Formosa, Aracruz, Brasil

Congreso; III Congresso Brasileiro de Mastozoologia; 2005

Abstract: We present the most comprehensive systematic study of Necromys, a rodent genus distributed in open areas north and south of Amazonia and in Andean grasslands. The study is based on sequences of the cytochrome b gene that were analyzed by parsimony and Bayesian approaches. The analyses include sequences of 62 specimens from 51 localities from Argentina, Bolivia, Brazil, Colombia, Paraguay, Peru, Uruguay, and Venezuela representing all but one of the species currently recognized in the genus. Among the results obtained we stress the following: Necromys was recovered monophyletic. We found a large polytomy at the base of Necromys that involves tree lineages. One represented by the Andean N. lactens, which shows a marked phylogeographic pattern. The second clade is formed by N. urichi from the northern grasslands of South America and N. amoenus from the central Andes. Results suggest that each of these taxa may represent more than one biological species. The third and last clade involved in the basal polytomy of Necromys is formed by lowland species found south of Amazonia. Within this clade N. obscurus is sister to the remaining species. Haplotypes recovered from specimens assigned to N. benefactus , N. temchuki, and N. lasiurus form a clade, but these taxa do not form reciprocally monophyletic groups; in addition, this large clade lacks geographic structure. These genealogical results, discussed in the context of genetic and morphologic variation, are the base of nomenclatorial, taxonomic, and biogeographic considerations.1 localities from Argentina, Bolivia, Brazil, Colombia, Paraguay, Peru, Uruguay, and Venezuela representing all but one of the species currently recognized in the genus. Among the results obtained we stress the following: Necromys was recovered monophyletic. We found a large polytomy at the base of Necromys that involves tree lineages. One represented by the Andean N. lactens, which shows a marked phylogeographic pattern. The second clade is formed by N. urichi from the northern grasslands of South America and N. amoenus from the central Andes. Results suggest that each of these taxa may represent more than one biological species. The third and last clade involved in the basal polytomy of Necromys is formed by lowland species found south of Amazonia. Within this clade N. obscurus is sister to the remaining species. Haplotypes recovered from specimens assigned to N. benefactus , N. temchuki, and N. lasiurus form a clade, but these taxa do not form reciprocally monophyletic groups; in addition, this large clade lacks geographic structure. These genealogical results, discussed in the context of genetic and morphologic variation, are the base of nomenclatorial, taxonomic, and biogeographic considerations.