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Puerto Madryn, Argentina

Pardinas U.F.J.,Centro Nacional Patagonico | Teta P.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia
Estudios Geologicos | Year: 2011

The sister genera Holochilus and Lundomys, plus the extinct forms Carletonomys and Noronhomys and the living Pseudoryzomys, constitute a small clade of amphibious sigmodontine rodents that inhabits in tropical and subtropical environments of the Neotropics. Based on almost all the available fossil evidence recovered in Argentina, Bolivia, southeastern Brazil, and Uruguay we revised the paleontological record of Holochilus and Lundomys in southern South America. Past distributions and chronologies indicate the following occurrences [biochrons] for the study area: Holochilus brasiliensis (Middle Pleistocene- Recent in Argentina, Late Pleistocene-Recent in Brazil), H. chacarius (Late Holocene-Recent in Argentina, Early Holocene-Recent in Bolivia), H. primigenius (Middle Pleistocene in Bolivia), and Lundomys molitor (Middle Pleistocene-Late Pleistocene in Argentina, Late Pleistocene-Recent in Uruguay). Taking into account the present distributions and environmental requirements of these rodents we hypothesize several expansion/retraction episodes of their populations triggered by the occurrence of moist/dry climatic pulses during Pleistocene-Holocene times.

Lessa E.P.,University of Montevideo | D'ElIa G.,University of Concepcion | PardiNas U.F.J.,Centro Nacional Patagonico
Molecular Ecology | Year: 2010

Species are impacted by climate change at both ecological and evolutionary time scales. Studies in northern continents have provided abundant evidence of dramatic shifts in distributions of species subsequent to the last glacial maximum (LGM), particularly at high latitudes. However, little is known about the history of southern continents, especially at high latitudes. South America is the only continent, other than Antarctica, that extends beyond 40 °S. Genetic studies of a few Patagonian species have provided seemingly conflicting results, indicating either postglacial colonization from restricted glacial refugia or persistence through glacial cycles and in situ differentiation. Using mitochondrial DNA sequences of 14 species of sigmodontine rodents, a major faunal ensemble of Patagonia and Tierra del Fuego, we show that at least nine of these species bear genetic footprints of demographic expansion from single restricted sources. However, timing of demographic expansion precedes the LGM in most of these species. Four species are fragmented phylogeographically within the region. Our results indicate that (i) demographic instability in response to historical climate change has been widespread in the Patagonian-Fueguian region, and is generally more pronounced at high latitudes in both southern and northern continents; (ii) colonization from lower latitudes is an important component of current Patagonian-Fueguian diversity; but (iii) in situ differentiation has also contributed to species diversity. © 2010 Blackwell Publishing Ltd.

Parada A.,Bernardo OHiggins University | Pardinas U.F.J.,Centro Nacional Patagonico | Salazar-Bravo J.,Texas Tech University | D'Elia G.,Austral University of Chile | Palma R.E.,Bernardo OHiggins University
Molecular Phylogenetics and Evolution | Year: 2013

With about 400 living species and 82 genera, rodents of the subfamily Sigmodontinae comprise one of the most diverse and more broadly distributed Neotropical mammalian clades. There has been much debate on the origin of the lineage or the lineages of sigmodontines that entered South America, the timing of entrance and different aspects of further diversification within South America. The ages of divergence of the main lineages and the crown age of the subfamily were estimated by using sequences of the interphotoreceptor retinoid binding protein and cytochrome b genes for a dense sigmodontine and muroid sampling. Bayesian inference using three fossil calibration points and a relaxed molecular clock estimated a middle Miocene origin for Sigmodontinae (∼12. Ma), with most tribes diversifying throughout the Late Miocene (6.9-9.4. Ma). These estimates together results of analyses of ancestral area reconstructions suggest a distribution for the most recent common ancestor of Sigmodontinae in Central-South America and a South American distribution for the most recent common ancestor of Oryzomyalia. © 2012 Elsevier Inc.

De la Sancha N.U.,University of Rhode Island | D'Elia G.,Austral University of Chile | Teta P.,Centro Nacional Patagonico
Mammalian Biology | Year: 2012

The subgenus . Marmosa (. Micoureus) Lesson, 1842 includes six species of long-tailed, black masked mouse-opossums widely distributed in forested areas of the Neotropics from northern Argentina to Belize. Most of the nominal forms of . Marmosa (. Micoureus) have not been revised since 1933 and some currently accepted synonymies are in need of revision; similarly distributions of these forms remain for the most part unclear. Herein, we report Paraguayan new and noteworthy locality records for . Marmosa (. Micoureus), including the first records for the western Dry Chaco region. Specimens were identified to the species level on the basis of morphological and molecular data. In addition, we conducted a phylogenetic analysis that includes sequences of five of the six species currently recognized of . Micoureus incorporating a total of 70 sequences of the subgenus. This constitute the most taxonomically and geographically dense phylogenetic analysis of . Micoureus. Results show that the most basal dichotomy of the . Micoureus clade does not delimit cis- and trans-Andean reciprocally monophyletic groups, rending the cis group paraphyletic to the single trans-species included, suggesting that the colonization of the western (trans) side of the Andes was a relatively late event in the biogeographic history of . Micoureus. In addition, the phylogenetic analysis shows that additional taxonomic work is much needed to clarify the number of distinct biological units, either species or subspecies, within . Micoureus. © 2011 Deutsche Gesellschaft für Säugetierkunde.

Pardinas U.F.J.,Centro Nacional Patagonico | Teta P.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia
Zootaxa | Year: 2011

We studied the holotype and only known specimen of the rodent Calomys anoblepas Winge, 1887, an enigmatic and putatively extinct pentalophodont sigmodontine found in the limestone caves of Lagoa Santa, Minas Gerais, Brazil. Comparisons with other sigmodontines suggest that anoblepas can be allocated under the genus Juliomys González, 2000 and probably represents an extinct form within it. Cranial characters that support our generic hypothesis include the combination of an interlacrymal depression behind nasals, anterior portion of interfrontal suture with incomplete fusion, zygomatic plate nearly vertical with almost nonexistent upper free border, anterior border of the mesopterygoid fossa located at the level of third molar hypoflexus, and brachyodont molars with crested coronal topography. Juliomys includes three living species of sylvan and arboreal mice endemic of the Atlantic forests. This genus is absent in contemporaneous rodent assemblage from Lagoa Santa area, suggesting different environmental conditions during Pleistocene deposition times. © 2011, Magnolia Press.

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