Browsing by Author "Rivera-Milla, E"

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    Phylogenetic and biogeographic relationships of the mouse opossum Thylamys (Didelphimorphia, Didelphidae) in southern South America
    (2002) Palma, RE; Rivera-Milla, E; Yates, TL; Marquet, PA; Meynard, AP
    Nucleotide sequence data from the mitochondrial cytochrome b gene were used to evaluate the phylogenetic relationships among mouse opossum species of the genus Thylamys. Based on approximately 1000 bp in five of the six species of the genus and including different localities for some of the species, we concluded that T. macrura from the subtropical forests of eastern Paraguay is the most primitive taxon. Subsequent radiation of the genus is explained mainly via founder effect speciation. This evolutionary scenario would account for the speciation of T pusilla, T venusta, T pallidior, and T elegans in the Chaco, southern Bolivia and northern Argentina, the Andean Altiplano, the Coastal Desert of Chile, and coastal Peru, respectively. Calibration of a molecular clock set the Pleistocene as the period for the differentiation of Thylamys species. The molecular results confirm the strong genetic connection between populations that inhabit the "pre-cordillera" of northern Chile (T pallidior) and the canyons that run through the Atacama Desert to the lowlands in northern Chile. Our results confirm the occurrence of two Thylamys species in Chile, T. pallidior and T. elegans, within and south to the Atacama Desert, respectively. (C) 2002 Elsevier Science (USA). All rights reserved.
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    Phylogeography of Oligoryzomys longicaudatus (Rodentia: Sigmodontinae) in temperate South America
    (2005) Palma, RE; Rivera-Milla, E; Salazar-Bravo, J; Torres-Pérez, F; Pardiñas, UFJ; Marquet, PA; Spotorno, AE; Meynard, AP; Yates, TL
    Phylogeographic relationships were evaluated at the intraspecific level using nucleotide sequence data from the mitochondrial cytochrome b gene of representative specimens of "colilargo" (Oligoryzomys longicaudatus) from 31 localities, along its distributional range over a large part of the western Andes and southern Argentina. Based on approximately 1,000 base pairs (bp), we recognized a single species on both the Chilean and the Argentinean side as far as at least latitude 51degreesS, rejecting the subspecific distinctiveness of longicaudatus and philippi. We thus placed the latter in full synonymy with O. longicaudatus as earlier studies proposed, and enlarged its range as far as Torres del Paine, about 51degreesS. The occurrence of subspecies in this range is doubtful given the low sequence divergence values and the absence of significant associations between haplotypes and their geography. Additionally, we hypothesized that the entrance of this species into the Chilean side of the Andes mountains occurred through the Patagonian forests of southern Argentina, with further dispersal to the north from the south.