A predictive distribution model for Andinomys edax (Rodentia: Cricetidae) in Argentina

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We studied the distribution of Andinomys edax (Rodentia, Cricetidae, Sigmodontinae) in northwestern Argentina. Presence data obtained from field records, museum specimens and literature were used to model the potential distribution of this species. Andinomys edax was known in Argentina from only 41 occurrence localities, most of them restricted to Jujuy province. Here we add new localities from Catamarca, Jujuy, Salta and Tucumán provinces. We used the maximum entropy method (Maxent) and seven environmental variables to produce a potential distribution map of the species. The 7.015 cumulative threshold (corresponding to the equal test of sensitivity and specificity) was the most efficient hypothetical distribution according to the omission rate. The area under the curve (AUC) was of 0.987 for training data. The model indicates that A. edax is mainly distributed on the more humid eastern montane ranges in the region, associated to high altitude grasslands and ecotonal zones between 1500 and 4000 m in Yungas, Prepuna, Puna and High Andean environments. These results, as well as the known fossil record for the species in Argentina, indicate the ecological plasticity of A. edax, present in the region at least since Middle-Upper Pleistocene times.


Un modelo predictivo de distribución para Andinomys edax (Rodentia: Cricetidae) en Argentina. Se estudió la distribución de Andinomys edax (Rodentia, Cricetidae, Sigmodontinae) en el noroeste de Argentina. Para modelar la distribución potencial de la especie se usaron datos de presencia obtenidos a partir de registros de campo, de especímenes depositados en colecciones y de la literatura. Andinomys edax se conocía en Argentina por sólo 41 localidades, la mayoría de ellas en la provincia de Jujuy. En este trabajo se adicionan nuevas localidades para las provincias de Catamarca, Jujuy, Salta y Tucumán. El mapa de distribución potencial de la especie fue modelado utilizando el método de máxima entropía (Maxent) y siete variables ambientales. De acuerdo con la tasa de omisión, el umbral acumulativo de 7.015 (correspondiente al test de igualdad de sensitividad y especificidad) determinó la distribución hipotética más eficiente. El área bajo la curva (AUC) para el test ROC fue de 0.987 para los datos de entrenamiento. De acuerdo con el modelo, A. edax se distribuye principalmente sobre las laderas orientales húmedas de los cordones montañosos de la región, asociada a pastizales de altura y sus ecotonos entre 1500 y 4000 m, en ambientes de Yungas, Prepuna, Puna y Altos Andes. Estos resultados, así como el registro fósil de la especie en Argentina, indican una gran plasticidad ecológica de A. edax, presente en la región al menos desde el Pleistoceno medio-superior.

Distribución de Necromys lactens y Phyllotis osilae (Rodentia: Cricetidae: Sigmodontinae) en el Noroeste argentino: modelos predictivos basados en el concepto de nicho ecológico

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Distribution of Necromys lactens and Phyllotis osilae (Rodentia: Cricetidae: Sigmodontinae) in northwestern Argentina: predictive models based on the concept of ecological niche. We used presence data from field records, museum specimens and literature sources to model the potential distribution of two species of sigmodontine rodents, Necromys lactens and Phyllotis osilae in northwestern Argentina, based on environmental variables. We used the DOMAIN program, which based on presence data defines the environmental space that imposes conditions to the species distribution. We worked with two data sets, one constituted only by reliable data and the other one constituted by these reliable data plus other information considered more doubtful because of its controvertible identification and location. The models obtained from the reliable data set were more efficient in the prediction of distribution than doubtful data, with Kappa index of 0.69 and 0.63 for Necromys lactens and Phyllotis osilae, respectively. These results indicate that both species are restricted to the upper portions of the most important mountains in the region and that their distribution consists of islands or patches immerse in a complex matrix of forest and semi-desert environment. Both species were associated to high altitude grasslands and ecotone environments between 1200 and 3200 m elevation, being P. osilae‘s distribution a little more extended than N. lactens.