Abrothrix

Abstract: Aim We evaluated the phylogeography of sigmodontine taxa of the genera Phyllotis and Abrothrix at the intra and interspecific level, in the Atacama desert and adjacent Andean and Puna regions of northern Chile. The major goal was to test the hypothesis that sigmodontine mice differentiated in the lowlands, most likely via peripatric speciation, dispersing from highland to lowland areas across the desert vegetated canyons, thus reaching the Pacific coast. Dispersing individuals may have found favourable habitats along these valleys, in northern Chile, which connect the high altitude Puna region with the lowlands. Location The study was conducted in northern Chile (18‐22! S), in coastal prePuna and Puna regions. Methods For phylogeographic analyses we analysed cytochrome b mitochondrial sequences for 29 specimens of the genera Abrothrix and Phyllotis, from the region of study. All results were analysed phylogenetically using maximum-likelihood, Bayesian, and uncorrected median-joining network methodology. Results In Phyllotis we recognized two major clusters of taxa: one restricted to the Puna region identified as Phyllotis xanthopygus chilensis, in close association to a pre-Punean and lowland clade constituted by Phyllotis limatus, on the western slopes of the Andes. A similar pattern was distinguished for Abrothrix, where Abrothrix andinus was recognized in the Andean Altiplano-pre-Puna region and Abrothrix olivaceus in the lowlands of northern Chile. Main conclusions We found that the radiation of sigmodontine mice in the central Andes may have been facilitated by the historical events that affected high Andean elevations during Pleistocene times, as well as changes in the vegetation composition and climate that started to prevail during that time. Our results also support previous hypotheses that the major mode of evolution for small mammals in the Andes region has been based on the founder effect or the peripheral isolates model, from a central range located in the Andes.

Abstract: On an East–West transect in northern Patagonia, the steppe-inhabiting mouse Akodon (or Abrothrix) xanthorhinus meets the forest-inhabiting Akodon (Abrothrix) olivaceus on the eastern side of the Andes where steppe meets forest In a contact zone of about 30 km, the mice are morphologically intermediate Nuclear (allozyme) and mitochondrial DNA analyses confirm that the genetic difference between eastern, western, and intermediate populations is not much greater than would be expected within individuals from a single population We conclude that xanthorhinus and olivaceus should be united under the species name olivaceus

Abstract: Analyses of morphological and molecular data indicate the existence of an unrecognized and unnamed species of soft-haired mouse, genus Abrothrix. Here, we name and describe this new species, which inhabits the Valdivian ecoregion, from the north of Chiloe Island onto the mainland in the Chilean regions of Los Lagos and Los Rios; it also occurs at a single locality in the Argentinean province of Neuquen. Long confused with A. sanborni, the new species presents a unique combination of characters that differentiate it in external, cranial, phallic, and dental terms from its congeners. Phylogenetic analysis, based on cytochrome-b gene sequences, indicates that the new species is sister to a clade formed by the austral species A. lanosa and A. sanborni and differs on average from them by 5.7% and 5.2%, respectively. Results based on the nuclear Fgb-I7 locus are less conclusive regarding the phylogenetic position of the new species but also show its distinction. We comment on the conservation significance of ou...