Browsing by Author "Boric-Bargetto, Dusan"

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    A 19 Year Analysis of Small Mammals Associated with Human Hantavirus Cases in Chile
    (2019) Torres-Perez, Fernando; Eduardo Palma, R.; Boric-Bargetto, Dusan; Vial, Cecilia; Ferres, Marcela; Vial, Pablo A.; Martinez-Valdebenito, Constanza; Pavletic, Carlos; Parra, Alonso; Marquet, Pablo A.; Mertz, Gregory J.
    Small mammals present in areas where hantavirus cardiopulmonary syndrome (HCPS) cases had occurred in central and southern Chile were captured and analyzed to evaluate the abundance of rodents and seroprevalence rates of antibodies to Andes orthohantavirus (ANDV). Sampling areas ranged from the Coquimbo to Aysen regions (30-45 degrees S approx.) regions. Ninety-two sites in peridomestic and countryside areas were evaluated in 19 years of sampling. An antibody against ANDV was detected by strip immunoassay in 58 of 1847 specimens captured using Sherman traps. Of the eleven species of rodents sampled, Abrothrix olivacea, Oligoryzomys longicaudatus and Abrothrix hirta were the most frequently trapped. O. longicaudatus had the highest seropositivity rate, and by logistic regression analysis, O. longicaudatus of at least 60 g had 80% or higher probability to be seropositive. Sex, age and wounds were significantly related to seropositivity only for O. longicaudatus. Across administrative regions, the highest seropositivity was found in the El Maule region (34.8-36.2 degrees S), and the highest number of HCPS cases was registered in the Aysen region. Our results highlight the importance of long term and geographically extended studies, particularly for highly fluctuating pathogens and their reservoirs, to understand the implications of the dynamics and transmission of zoonotic diseases in human populations.
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    Glaciation Effects on the Phylogeographic Structure of Oligoryzomys longicaudatus (Rodentia: Sigmodontinae) in the Southern Andes
    (2012) Eduardo Palma, R.; Boric-Bargetto, Dusan; Torres-Perez, Fernando; Hernandez, Cristian E.; Yates, Terry L.
    The long-tailed pygmy rice rat Oligoryzomys longicaudatus (Sigmodontinae), the major reservoir of Hantavirus in Chile and Patagonian Argentina, is widely distributed in the Mediterranean, Temperate and Patagonian Forests of Chile, as well as in adjacent areas in southern Argentina. We used molecular data to evaluate the effects of the last glacial event on the phylogeographic structure of this species. We examined if historical Pleistocene events had affected genetic variation and spatial distribution of this species along its distributional range. We sampled 223 individuals representing 47 localities along the species range, and sequenced the hypervariable domain I of the mtDNA control region. Aligned sequences were analyzed using haplotype network, Bayesian population structure and demographic analyses. Analysis of population structure and the haplotype network inferred three genetic clusters along the distribution of O. longicaudatus that mostly agreed with the three major ecogeographic regions in Chile: Mediterranean, Temperate Forests and Patagonian Forests. Bayesian Skyline Plots showed constant population sizes through time in all three clusters followed by an increase after and during the Last Glacial Maximum (LGM; between 26,000-13,000 years ago). Neutrality tests and the "g" parameter also suggest that populations of O. longicaudatus experienced demographic expansion across the species entire range. Past climate shifts have influenced population structure and lineage variation of O. longicaudatus. This species remained in refugia areas during Pleistocene times in southern Temperate Forests (and adjacent areas in Patagonia). From these refugia, O. longicaudatus experienced demographic expansions into Patagonian Forests and central Mediterranean Chile using glacial retreats.
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    Mountaintops phylogeography: a case study using small mammals from the Andes and the coast of central Chile
    (2017) Palma Vásquez, Ramón Eduardo; Gutiérrez-Tapia, Pablo; González, Juan Francisco; Boric-Bargetto, Dusan; Torres-Pérez, Fernando
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    Phylogenetic evaluation of taxonomic definition of didelphid mouse opossum of the genus Thylamys from valleys of Coquimbo region, Chile
    (2016) Boric-Bargetto, Dusan; Zuniga-Reinoso, Alvaro; Cancino, Ricardo A.; Gonzalez-Acuna, Daniel; Rodriguez-Serrano, Enrique; Eduardo Palma, R.; Hernandez, Cristian E.
    Only two species of Didelphidae are currently recognized in Chile, the sister species Thylamys elegans, endemic of Mediterranean ecorregion and Thylamys pallidior, the inhabitant of the Puna and desert canyons. Three subspecies have been described for T. elegans: T. e. elegans, T. e. coquimbensis and T. e. soricinus. However, a recent study based on morphological analyses, synonymized T. elegans coquimbensis from the Coquimbo valleys (30-31 degrees S) with T. pallidior and proposed that T. elegans and T. pallidior could be in sympatry at Coquimbo valleys between Fray Jorge (30 degrees 40'S) and Paiguano (30 degrees 02'S). We assess the current definition of T. e. coquimbensis and T. e. elegans, as well as this taxonomical conflict among the mouse opossums from the Coquimbo valleys through phylogenetic analyses of cytochrome b mitochondrial gene sequences. In this study, for the first time, we used specimens from the type localities of T. e. coquimbensis and T. e. elegans. In addition, we analyzed diagnostic cranial structures for this taxonomic revision. The results supported two allopatric clades, allowing us to keep the taxonomic definition of T. e. elegans and T. e. coquimbensis as phylogenetic reciprocal monophyletic clades and polyphyletic with T. pallidior. This result corroborates previous morphological analyses, which support that mouse opossums from the Coquimbo valleys are T. e. coquimbensis, thus extending its geographic distribution to the coast of Coquimbo and Atacama regions. We don't have evidence for sympatric distribution between T. elegans and T. pallidior in the Coquimbo region.