Browsing by Author "Gonzalez-Acuna, Daniel"

Now showing 1 - 8 of 8
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    Chinstrap penguin population genetic structure: one or more populations along the Southern Ocean?
    (2018) Mura-Jornet, Isidora; Pimentel, Carolina; Dantas, Gisele P. M.; Petry, Maria Virginia; Gonzalez-Acuna, Daniel; Barbosa, Andres; Lowther, Andrew D.; Kovacs, Kit M.; Poulin, Elie; Vianna, Juliana
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    Have Historical Climate Changes Affected Gentoo Penguin (Pygoscelis papua) Populations in Antarctica?
    (2014) Pena M., Fabiola; Poulin, Elie; Dantas, Gisele P. M.; Gonzalez-Acuna, Daniel; Petry, Maria Virginia; Vianna, Juliana A.
    The West Antarctic Peninsula (WAP) has been suffering an increase in its atmospheric temperature during the last 50 years, mainly associated with global warming. This increment of temperature trend associated with changes in sea-ice dynamics has an impact on organisms, affecting their phenology, physiology and distribution range. For instance, rapid demographic changes in Pygoscelis penguins have been reported over the last 50 years in WAP, resulting in population expansion of sub-Antarctic Gentoo penguin (P. papua) and retreat of Antarctic Adelie penguin (P. adeliae). Current global warming has been mainly associated with human activities; however these climate trends are framed in a historical context of climate changes, particularly during the Pleistocene, characterized by an alternation between glacial and interglacial periods. During the last maximal glacial (LGM similar to 21,000 BP) the ice sheet cover reached its maximum extension on the West Antarctic Peninsula (WAP), causing local extinction of Antarctic taxa, migration to lower latitudes and/or survival in glacial refugia. We studied the HRVI of mtDNA and the nuclear intron beta fibint7 of 150 individuals of the WAP to understand the demographic history and population structure of P. papua. We found high genetic diversity, reduced population genetic structure and a signature of population expansion estimated around 13,000 BP, much before the first paleocolony fossil records (similar to 1,100 BP). Our results suggest that the species may have survived in peri-Antarctic refugia such as South Georgia and North Sandwich islands and recolonized the Antarctic Peninsula and South Shetland Islands after the ice sheet retreat.
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    Isolation of drug-resistant Salmonella enterica serovar enteritidis strains in gentoo penguins from Antarctica
    (2017) Retamal, Patricio; Llanos-Soto, Sebastian; Moreno Salas, Lucila; Lopez, Juana; Vianna, Juliana; Hernandez, Jorge; Medina-Vogel, Gonzalo; Castaneda, Francisco; Fresno, Marcela; Gonzalez-Acuna, Daniel
    Anthropogenic activity in Antarctica constitutes a continuous risk for the introduction of infectious diseases into indigenous wildlife populations. Penguin colonies living close to human settlements or inhabiting in areas considered for tourism could be facing a greater threat of infection. Fecal samples from Pygoscelis penguins (Pygoscelis spp.) were collected from different sites within Antarctic Peninsula and South Shetlands Islands in order to assess the presence of Salmonella enterica. Bacterial identification and characterization was performed applying biochemical and molecular techniques. Isolates were tested for antimicrobial resistance by the disk diffusion method, and PCR analyses were used for detection of resistance and virulence-associated genes. Four samples (1.74%) from P. papua were found to be positive to S. enterica serovar Enteritidis strains. All of them showed phenotypic antimicrobial resistance to at least three antimicrobials, and shared a similar gene profile through PCR. Results in this study urgently call for improvements in sanitary standards for waste disposal and sewage treatment in Antarctica. To our knowledge, this is the first study to report antimicrobial resistance in S. enterica isolated from Antarctic wild species.
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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.
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    Presence of Ixodes neuquenensis Ringuelet, 1947 (Acari: Ixodidae) on the endangered Neotropical marsupial Monito del Monte (Dromiciops gliroides Thomas, 1894, Microbiotheria: Microbiotheriidae) at Chiloe Island, Chile
    (2007) Marin-Vial, Paula; Gonzalez-Acuna, Daniel; Celis-Diez, Juan L.; Cattan, Pedro E.; Guglielmone, Alberto A.
    The presence of Ixodes neuquenensis (Ringuelet, Notas Mus la Plata 12:207-216, 1947) (Acari: Ixodidae) parasitizing populations of Dromiciops gliroides Thomas, 1894 (Microbiotheria: Microbiotheriidae) at Chiloe Island confirms that this tick species is established in Chile. No preference of the ticks for sex or age of the host was observed.
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    Report on beak abnormalities of some birds of Patagonia
    (2018) Valdebenito, Jose O.; Grandon-Ojeda, Alexandra; Pantoja-Maggi, Vicente; Novoa, Fernando J.; Gonzalez-Acuna, Daniel
    Avian beaks are complex and highly specialized structures that if altered could hinder many aspects of bird biology. Here, we provide evidence from incidental sightings of 24 birds from 9 species presenting a mild to severe degree of beak abnormality, including species from Passeriformes, Falconiformes, Sphenisciformes, and Charadriiformes, recorded in Chile (2013-2016). The most common alterations corresponded to crossed beaks and excessive elongation of the upper beak (25% each). The Austral Thrush (Turdus falcklandii; n = 11) and Chilean Mockingbird (Mimus thenca; n = 5) were the birds most frequently recorded with abnormalities. With the exception of the Austral Thrush and Magellanic Penguin (Spheniscus magellanicus), all beak abnormalities mentioned here are the first recorded for each species.
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    Species delimitation and intraspecific diversification in recently diverged South American foxes
    (2024) Pizarro, Eduardo J.; Julio-Kalajzic, Bernardita; Sallaberry-Pincheira, Nicole; Munoz, Valentina; Gonzalez-Acuna, Daniel; Cabello, Javier; Acosta-Jamett, Gerardo; Bonacic, Cristian; Iriarte, Agustin; Rodriguez, Alejandro; Travaini, Alejandro; Cevidanes, Aitor; Brito, Jose Luis; Millan, Javier; Marin, Juan Carlos; Vianna, Juliana A.
    The divergence between the Andean fox (Lycalopex culpaeus) and the South American gray fox (L. griseus) represents a recent speciation event in South America. These taxa are partially sympatric and share biological, morphological, and ecological traits. Previous studies failed to recover reciprocal monophyly, suggesting the occurrence of introgression or incomplete lineage sorting (ILS). Here, we obtained mitochondrial and nuclear markers for 140 L. culpaeus and 134 L. griseus from the Southern Cone of South America to assess their inter and intraspecific divergence. We recovered reciprocal monophyly of L. culpaeus and L. griseus, with mild signatures of introgression or ILS. Therefore, taxonomic misidentification and the use of a limited number of markers may be the main reason behind the past debate about the delimitation of both species. Two main divergent clades were found in L. culpaeus with a phylogeographical boundary in the High Plateau of northeastern Chile. The southern clade along with three northern sub-clades corresponded to four morphological subspecies. Less genetic differentiation was found in L. griseus with a spatial population structure that does not support the occurrence of distinct subspecies. The results found in this study suggest the extant evolutionary significant units that need to be considered for biological conservation management of these species.
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    Uncovering population structure in the Humboldt penguin (Spheniscus humboldti) along the Pacific coast at South America
    (2019) Dantas, Gisele P. M.; Oliveira, Larissa R.; Santos, Amanda M.; Flores, Mariana D.; de Melo, Daniella R.; Simeone, Alejandro; Gonzalez-Acuna, Daniel; Luna-Jorquera, Guillermo; Le Bohec, Celine; Valdes-Velasquez, Armando; Cardena, Marco; Morgante, Joao S.; Vianna, Juliana A.
    The upwelling hypothesis has been proposed to explain reduced or lack of population structure in seabird species specialized in food resources available at cold-water upwellings. However, population genetic structure may be challenging to detect in species with large population sizes, since variation in allele frequencies are more robust under genetic drift. High gene flow among populations, that can be constant or pulses of migration in a short period, may also decrease power of algorithms to detect genetic structure. Penguin species usually have large population sizes, high migratory ability but philopatric behavior, and recent investigations debate the existence of subtle population structure for some species not detected before. Previous study on Humboldt penguins found lack of population genetic structure for colonies of Punta San Juan and from South Chile. Here, we used mtDNA and nuclear markers (10 microsatellites and RAG1 intron) to evaluate population structure for 11 main breeding colonies of Humboldt penguins, covering the whole spatial distribution of this species. Although mtDNA failed to detect population structure, microsatellite loci and nuclear intron detected population structure along its latitudinal distribution. Microsatellite showed significant R-st values between most of pairwise locations (44 of 56 locations, R-st = 0.003 to 0.081) and 86% of individuals were assigned to their sampled colony, suggesting philopatry. STRUCTURE detected three main genetic clusters according to geographical locations: i) Peru; ii) North of Chile; and iii) Central-South of Chile. The Humboldt penguin shows signal population expansion after the Last Glacial Maximum (LGM), suggesting that the genetic structure of the species is a result of population dynamics and foraging colder water upwelling that favor gene flow and phylopatric rate. Our findings thus highlight that variable markers and wide sampling along the species distribution are crucial to better understand genetic population structure in animals with high dispersal ability.