Browsing by Autor "Luis A. Ebensperger"

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Phylogeography and demographic history of the Andean degu,<i>Octodontomys gliroides</i>(Rodentia: Octodontidae)
(Oxford University Press, 2016) Daniela S. Rivera; Juliana A. Vianna; Luis A. Ebensperger; R. Eduardo Palma
The Andean degu, Octodontomys gliroides Gervais & d'Orbigny, 1844, has a broad distribution inhabiting pre-Andean pre-Puna and Puna environments of tropical South America. In order to understand the phylogeographic patterns of Octodontomys gliroides, we sequenced 579 bp of the mitochondrial DNA control region from 100 individuals collected from 20 populations across its entire distributional range. The phylogenetic and parsimony network, in conjunction with analysis of molecular variance (AMOVA), revealed a structured pattern of geographic differentiation of O. gliroides, with the occurrence of two well-defined evolutionary lineages: lineage A, restricted to Bolivia and Chile, and lineage B, restricted mainly to Argentina. Analysis of population structure inferred three genetic clusters along the distribution of O. gliroides that mostly agree with the four major barriers inferred by BARRIER analysis (e.g. rivers, salt flats, deserts, and mountain systems). In addition to the significant differentiation found among all levels studied, a positive correlation was identified between genetic and geographic distance, similar to as expected under the isolation-by-distance model. The most recent common ancestor of O. gliroides was estimated as c. 5.99 Mya, and the divergence between lineages A and B is estimated to have occurred by the Middle Pleistocene, about 0.69 Mya. The mismatch distributions and neutrality tests suggested a signal of population range expansion for both lineages coincident with major climatic changes that occurred during the wet-dry events of the Pleistocene in the Andean Puna region. Bayesian skyline plots (BSPs) for lineage A suggest a long history of constant population size followed by a period of slight to moderate demographic expansion at c. 0.04 Mya, whereas lineage B remained unclear after BSP analysis, probably because of the limited sample size.
Sociality of<i>Octodontomys gliroides</i>and other octodontid rodents reflects the influence of phylogeny
(Oxford University Press, 2014) Daniela S. Rivera; Sebastián Abades; Fernando D. Alfaro; Luis A. Ebensperger
Multiple ecological factors are known to drive variation in social behavior. However, group-living in some species appears to be highly conserved, suggesting a phylogenetic influence. In this study, we evaluated both scenarios using intraspecific and interspecific comparisons across octodontid rodents. We first examined 2 different populations of Andean degu (Octodontomys gliroides), representing 2 extremes of a climate vegetation gradient across the Andes range. We evaluated how ecological variation in terms of abundance and distribution of food resources, predation risk, and burrowing costs predicted interpopulation variation in group size and range-area overlap (2 proxies of sociality). We estimated these measures of sociality from livetrapping and radiotelemetry. We then used phylogenetic methods to determine whether sociality exhibits a phylogenetic signal and reconstructed the ancestral state of sociality across the family Octodontidae. Overall activity of females and males of O. gliroides was greater during nighttime than daytime. Across populations we found significant differences in ecology, including abundance and distribution of food, predation risk, and burrowing costs. However, populations were similar in terms of group size and range-area overlap. The phylogenetic approach revealed a strong and significant phylogenetic signal associated with sociality, where this behavior was present early during the evolution of octodontid rodents. Together, these findings imply that sociality of O. gliroides is not linked to current population differences in ecology.