DSpace Angular :: Browsing by Author "Vianna, Juliana"

Browsing by Author "Vianna, Juliana"

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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
Climate change and population persistence in a hibernating marsupial
(2024) Nespolo, Roberto F.; Quintero-Galvis, Julian F.; Fonturbel, Francisco E.; Cubillos, Francisco A.; Vianna, Juliana; Moreno-Meynard, Paulo; Rezende, Enrico L.; Bozinovic, Francisco
Climate change has physiological consequences on organisms, ecosystems and human societies, surpassing the pace of organismal adaptation. Hibernating mammals are particularly vulnerable as winter survival is determined by short-term physiological changes triggered by temperature. In these animals, winter temperatures cannot surpass a certain threshold, above which hibernators arouse from torpor, increasing several fold their energy needs when food is unavailable. Here, we parameterized a numerical model predicting energy consumption in heterothermic species and modelled winter survival at different climate change scenarios. As a model species, we used the arboreal marsupial monito del monte (genus Dromiciops), which is recognized as one of the few South American hibernators. We modelled four climate change scenarios (from optimistic to pessimistic) based on IPCC projections, predicting that northern and coastal populations (Dromiciops bozinovici) will decline because the minimum number of cold days needed to survive the winter will not be attained. These populations are also the most affected by habitat fragmentation and changes in land use. Conversely, Andean and other highland populations, in cooler environments, are predicted to persist and thrive. Given the widespread presence of hibernating mammals around the world, models based on simple physiological parameters, such as this one, are becoming essential for predicting species responses to warming in the short term.
Cryptic speciation in gentoo penguins is driven by geographic isolation and regional marine conditions: Unforeseen vulnerabilities to global change
(2020) Pertierra, Luis R.; Segovia, Nicolás I.; Noll, Daly; Martínez, Pablo A.; Pliscoff, Patricio; Barbosa, Andrés; Vianna, Juliana; Aragón, Pedro; Raya Rey, Andrea; Pistorius, Pierre; Trathan, Phil; Polanowski, Andrea; Bonadonna, Francesco; Le Bohec, Célin; Bi, Ke; Wang-Claypool, Cynthia Y.; González Acuña, Daniel; Dantas, Gisele P. M.; Bowie, Rauri C. K.; Poulin, Elie
Diagnóstico del estado nacional de la conservación ex situ de semillas en Chile y estudio de caso : colección de semillas del Jardín Botánico Chagual
(2022) Bustos Donoso, María Fernanda; Vianna, Juliana; Pontificia Universidad Católica de Chile. Facultad de Agronomía e Ingeniería Forestal
Conscientes del valor intrínseco de la diversidad biológica y preocupados por la amenaza que constituye su pérdida para el bienestar humano, el Convenio sobre la Diversidad Biológica advirtió que se requieren grandes desafíos para frenar la pérdida de biodiversidad, entre ellos, conservar al menos el 75% de las plantas amenazadas en colecciones ex situ. El presente estudio se formuló bajo dos hipótesis: Chile no está alcanzando este objetivo, y el porcentaje de plantas nativas conservadas en colecciones de semillas es bajo respecto del total. Para abordar esta premisa se realizó un diagnóstico sobre el estado nacional de conservación ex situ de flora en base a colecciones de semillas y se expusieron los esfuerzos que distintas instituciones están realizando en torno a esta práctica, constatando que no existe suficiente información para conocer exactamente qué especies se están conservando, principalmente porque los esfuerzos de conservación son aislados y no se está actuando en red. Por otra parte, se verificó que Chile no tiene metas nacionales relacionadas con la Estrategia Mundial de Conservación de Especies Vegetales, por lo que se discutió sobre la importancia de avanzar hacia una estrategia nacional, incluyendo una mirada propositiva para que ésta logre dar cumplimiento a las metas globales de conservación ex situ promovidas por el Convenio. Adicionalmente, se analizó la colección de semillas del Jardín Botánico Chagual, con el propósito de iniciar la construcción de una base de información consolidada, que contribuya a la toma de decisiones futuras para priorizar la conservación de especies y sus hábitats.
Domestic dog and alien North American mink as reservoirs of infectious diseases in the endangered Southern river otter
(2022) Barros, Macarena; Pons, Daniel J.; Moreno, Andrea; Vianna, Juliana; Ramos, Barbara; Duenas, Fernando; Coccia, Cristina; Saavedra-Rodriguez, Roberto; Santibanez, Alexis; Medina-Vogel, Gonzalo
Introduced alien carnivores are host to infectious diseases that may become an important threat for native carnivore species conservation. Canine distemper virus (CDV) is thought to be transmitted among individuals by direct contact and to present viral dynamics associated with a density-dependent multi-host carnivore community. In contrast, Canine Parvovirus (CPV) is mostly transmitted by indirect contact and does not depend only on the density, but also on the social behaviour of infected as well as susceptible hosts. The objective of this study was to assess how introduced American mink (Neovison vison) can act as a bridge-host between domestic dog (Canis familiaris) and Southern river otter (Lontra provocax) in different dog and mink population density scenarios. Our data show that otters are seropositive to both CDV and PV, as well as a molecular identity to Parvovirus in dogs and minks. Furthermore, a strong positive correlation between dog population density and observed seroprevalence of CDV in dogs, minks, and otters was recorded. For Parvovirus, the observed seroprevalence in mink and otters was not correlated to a higher dog population density, but instead a relationship between dog and mink population densities and social behaviour. Our results suggest that introduced American mink and domestic dogs are reservoirs of CDV and PV, both being diseases of major importance for the conservation of native endangered carnivores in Patagonia.
Filogeografía y estructura genética poblacional del Rayadito de cola espinosa (Aphrastura spinicauda), un paseriforme ampliamente distribuido en Chile (30°S – 56°S)
(2021) Ortiz Carvajal, Gustavo; Vianna, Juliana; Pliscoff, Patricio; Pontificia Universidad Católica de Chile. Facultad de Agronomía e Ingeniería Forestal
La investigación sobre la distribución de la diversidad genética entre las poblaciones nos permite inferir procesos ecológicos relacionados con su conectividad. También nos permite identificar los factores que contribuyen a su estructura y demografía. Aunque las aves tienden a mostrar una baja estructura genética debido a su alta capacidad de dispersión, se ha informado de una fuerte presión de diferenciación en islas terrestres y oceánicas. Evaluamos la estructura genética poblacional, filogeografía, historia demográfica y adecuación climática pasada, actual y futura del Rayadito de Cola Espinosa (Aphrastura spinicauda), un paseriforme endémico del bosque templado del sur de Sudamérica, que se distribuye en un amplio rango latitudinal (30°S - 56°S) en Chile y el oeste de Argentina. Mediante el análisis del genoma completo, estudiamos 50 muestras de cinco localidades distribuidas dentro del rango geográfico de la especie en Chile. Utilizando métodos de estructuración genética, algoritmos de agrupamiento e identificación de barreras biogeográficas, encontramos evidencias que apoyan una estructura genética moderada y una serie de barreras espaciales que limitan el flujo génico hacia las poblaciones de Fray Jorge e Isla Mocha, favoreciendo su diferenciación. Por otro lado, no encontramos evidencia que apoye la validez de la subespecie A. s. fulva, descrita para las islas Chiloé y Chonos. Mediante los análisis de historia demográfica y modelos distribución de especie, hallamos evidencia que apoyaría la existencia de posibles refugios glaciares durante el Último Máximo Glacial para la especie. Finalmente, nuestros mapas de idoneidad climática destacan la importancia actual y futura de proteger áreas continentales costeras y ponen de manifiesto el riesgo de las poblaciones del centro y norte.
Is the environment shaping the genetic structure of the Humboldt penguin population?
(2019) Muñoz Farías, Valentina; Vianna, Juliana; Pontificia Universidad Católica de Chile. Facultad de Agronomía e Ingeniería Forestal
La especialización a sistemas altamente productivos y heterogéneos (como la corriente de Humboldt) podría llevar a filopatría y a una estructura genética, debido a condiciones locales favorables. O bien, puede promover movimientos durante episodios de calentamiento del agua, que impulsan la dispersión y el flujo génico. Aunque estudios previos ya han establecido la estructura genética del pingüino de Humboldt (Spheniscus humboldti), el papel del medio ambiente sobre este patrón no se ha estudiado antes. Utilizamos una aproximación de genoma completo con SNPs neutrales análisis de redundancia (RDA) para dar cuenta de la estructura genética del pingüino de Humboldt y su asociación con el entorno geográfico y ambiental de su rango de distribución. Encontramos una estructura genética leve, aunque significativa, con tres grupos genéticos: primero, la colonia peruana Punta San Juan; segundo Chañaral, la principal colonia chilena; y un grupo que comprende las colonias chilenas restantes (Pan de Azúcar, Isla Choros, Cachagua y Puñihuil). Aunque la prueba de Mantel para el aislamiento por distancia (IBD) no fue significativa, la significación estadística del vector latitudinal (dbMEM1) en dos de nuestros modelos RDA, podría ser un indicador de IBD. Lo anterior ya que la latitud se muestra como el factor principal que separa al extremo norte, la localidad Punta San Juan en Perú, de las colonias chilenas. Además, la clorofila-a, como indicador de productividad primaria, también fue significativa en nuestro modelo de RDA, lo que sugiere que la estructura genética encontrada podría ser producto de las condiciones ambientales locales. Destacamos la importancia de la configuración geográfica y ambiental del Sistema de Corriente de Humboldt sobre la estructura genética de la población de S. humboldti. Por lo tanto, en el escenario de un acelerado cambio climático, la estructura genética, que está determinada por las condiciones locales en un gradiente latitudinal, debe tenerse en cuenta al considerar las estrategias de manejo y conservación para esta especie vulnerable.
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.
Landscape genomics: natural selection drives the evolution of mitogenome in penguins
(2018) Ramos, Barbara.; Miranda, Marcelo; Vianna, Juliana; González Acuña, Daniel; Loyola, David E.; Johnson, Warren E.; Parker, Patricia G.; Massaro, Melanie.; Dantas, Gisele P.M.
Abstract Background Mitochondria play a key role in the balance of energy and heat production, and therefore the mitochondrial genome is under natural selection by environmental temperature and food availability, since starvation can generate more efficient coupling of energy production. However, selection over mitochondrial DNA (mtDNA) genes has usually been evaluated at the population level. We sequenced by NGS 12 mitogenomes and with four published genomes, assessed genetic variation in ten penguin species distributed from the equator to Antarctica. Signatures of selection of 13 mitochondrial protein-coding genes were evaluated by comparing among species within and among genera (Spheniscus, Pygoscelis, Eudyptula, Eudyptes and Aptenodytes). The genetic data were correlated with environmental data obtained through remote sensing (sea surface temperature [SST], chlorophyll levels [Chl] and a combination of SST and Chl [COM]) through the distribution of these species. Results We identified the complete mtDNA genomes of several penguin species, including ND6 and 8 tRNAs on the light strand and 12 protein coding genes, 14 tRNAs and two rRNAs positioned on the heavy strand. The highest diversity was found in NADH dehydrogenase genes and the lowest in COX genes. The lowest evolutionary divergence among species was between Humboldt (Spheniscus humboldti) and Galapagos (S. mendiculus) penguins (0.004), while the highest was observed between little penguin (Eudyptula minor) and Adélie penguin (Pygoscelis adeliae) (0.097). We identified a signature of purifying selection (Ka/Ks < 1) across the mitochondrial genome, which is consistent with the hypothesis that purifying selection is constraining mitogenome evolution to maintain Oxidative phosphorylation (OXPHOS) proteins and functionality. Pairwise species maximum-likelihood analyses of selection at codon sites suggest positive selection has occurred on ATP8 (Fixed-Effects Likelihood, FEL) and ND4 (Single Likelihood Ancestral Counting, SLAC) in all penguins. In contrast, COX1 had a signature of strong negative selection. ND4 Ka/Ks ratios were highly correlated with SST (Mantel, p-value: 0.0001; GLM, p-value: 0.00001) and thus may be related to climate adaptation throughout penguin speciation. Conclusions These results identify mtDNA candidate genes under selection which could be involved in broad-scale adaptations of penguins to their environment. Such knowledge may be particularly useful for developing predictive models of how these species may respond to severe climatic changes in the future.
Mapping the distribution and risk factors of Anaplasmataceae in wild and domestic canines in Chile and their association with Rhipicephalus sanguineus species complex lineages
(Elsevier GmbH, 2021) Di Cataldo, S.; Cevidanes, A.; Ulloa-Contreras, C.; Hidalgo-Hermoso, E.; Gargano, V.; Sacristán, I.; Sallaberry-Pincheira, N.; Peñaloza-Madrid, D.; González-Acuña, D.; Napolitano, C.; Vianna, Juliana; Acosta-Jamett, G.; Vicari, D.; Millán, J.
Anaplasma platys and Ehrlichia canis are members of the Anaplasmataceae family that cause disease in dogs and are mainly transmitted by Rhipicephalus sanguineus species group ticks. We performed a cross-sectional study on these pathogens across six bioclimatic regions of Chile, including 719 free-ranging rural dogs, 132 Andean foxes (Lycalopex culpaeus), and 82 South American gray foxes (Lycalopex griseus). Dog and fox blood samples were first screened for DNA of Anaplasmataceae followed by two Ehrlichia-specific protocols. Antibodies against Anaplasma sp. and E. canis were assessed by immunofluorescence in dogs. Ectoparasites were collected and identified, with the determination of the lineages of the Rhipicephalus sanguineus species group by molecular and phylogenetic analyses. Finally, potential risk factors for infection were investigated across the different bioclimatic regions and host species. All DNA amplicons obtained from the screening protocol corresponded to Anaplasma platys. The occurrence of both A. platys DNA and antibodies was confirmed in all six bioclimatic regions, except for regions at high altitude and/or without either R. sanguineus species group lineage present. Dogs infested with R. sanguineus ticks were significantly more prone to be infected and exposed to Anaplasma spp. Prevalence of DNA was significantly higher in juvenile (19%) than in adult dogs (9%), whereas the opposite was found for seroprevalence (19% versus 35%, respectively). Overall prevalence of A. platys DNA was higher in dogs (11%) than in foxes (4%), probably owing to markedly lower tick infestations in the foxes. Ehrlichia canis DNA was not detected in any sample, and antibodies against this pathogen were detected only in four dogs, in areas with both R. sanguineus lineages present. Free-ranging dogs in Chile could be favoring the maintenance of A. platys in all areas suitable for its tick vector. Although apparently infrequent, spillovers from dogs to foxes may be taking place and should be considered in management plans in Chile.
Phylogeography of the Marine Otter (Lontra felina): Historical and Contemporary Factors Determining Its Distribution
(2010) Vianna, Juliana; Ayerdi Retamales, Paula Andrea.; Faugeron, Sylvain Wielfrid
Spatial distribution, prevalence and diversity of haemosporidians in the rufous-collared sparrow, Zonotrichia capensis
(2019) Doussang, Daniela.; González Acuña, Daniel.; Torres Fuentes, Luis G.; Lougheed, Stephen C.; Clemente Carvalho, Rute B.; Greene, Kian C.; Vianna, Juliana
Abstract Background Parasite prevalence and diversity are determined by the distribution of hosts and vectors and by the interplay among a suite of environmental factors. Distributions of parasite lineages vary based on host susceptibility and geographical barriers. Hemoparasites of the genera Haemoproteus and Plasmodium have wide distributions, and high prevalence and genetic diversity within perching birds (Order Passeriformes). The rufous-collared sparrow (Zonotrichia capensis) is widely distributed in Central and South America across an immense diversity of environments from sea level to more than 4000 meters above sea level. It therefore provides an excellent model to investigate whether altitudinal and latitudinal gradients influence the distribution, prevalence and diversity of haemosporidian parasites, their population structure and the biogeographical boundaries of distinct parasite lineages. Results We assembled samples from 1317 rufous-collared sparrows spanning 75 locales from across Central and South America (between 9.5°N and 54°S; 10–4655 meters above sea level). We used DNA sequence data from a fragment of the mitochondrial cytochrome b gene (cytb) of Haemoproteus and Plasmodium from 325 positive samples and found prevalences of 22 and 3%, respectively. Haemoproteus exhibited a higher prevalence than Plasmodium but with comparatively lower genetic diversity. We detected a relationship of Plasmodium and Haemoproteus prevalence with altitude and latitude; however, altitude and latitude did not influence parasite diversity. Conclusions Parasite lineages showed a phylogeographical boundary coincident with the Andes Mountains, although we also observed a north-south disjunction in Peru for Haemoproteus. Haemosporidian distribution was not homogeneous but differed based on latitude and altitude. This is most probably due to environmental factors that have influenced both vector distribution and abundance, as well as parasite development. Our study provides key insights on the distribution of haemoparasite lineages and parasite dynamics within hosts.
Widespread Infection with Hemotropic Mycoplasmas in Free-Ranging Dogs and Wild Foxes Across Six Bioclimatic Regions of Chile
(MDPI, 2021) Di Cataldo, Sophia; Cevidanes, Aitor; Ulloa Contreras, Claudia; Sacristan, Irene; Penaloza Madrid, Diego; Vianna, Juliana; Gonzalez Acuna, Daniel; Sallaberry Pincheira, Nicole; Cabello, Javier; Napolitano, Constanza; Hidalgo Hermoso, Ezequiel; Acosta Jamett, Gerardo; Millan, Javier
Blood samples of 626 rural dogs, 140 Andean foxes (Lycalopex culpaeus), and 83 South American grey foxes (L. griseus) from six bioregions of Chile spanning 3000 km were screened for Mycoplasma DNA by conventional PCR and sequencing. Risk factors of infection were inferred using Generalized Linear Mixed Models and genetic structure by network analyses. Overall, Mycoplasma haemocanis/Mycoplasma haemofelis (Mhc/Mhf) and Candidatus Mycoplasma haematoparvum (CMhp) observed prevalence was 23.8% and 12.8% in dogs, 20.1% and 7.2% in Andean foxes, and 26.5% and 8.4% in grey foxes, respectively. Both hemoplasmas were confirmed in all the bioregions, with higher prevalence in those where ticks from the Rhipicephalus sanguineus species group were absent. Candidatus M. haematominutum and a Mycoplasma sp. previously found in South American carnivores were detected in one fox each. Although the most prevalent Mhc/Mhf and CMhp sequence types were shared between dogs and foxes, network analysis revealed genetic structure of Mhc/Mhf between hosts in some regions. Male sex was associated with a higher risk of Mhc/Mhf and CMhp infection in dogs, and adult age with CMhp infection, suggesting that direct transmission is relevant. No risk factor was identified in foxes. Our study provides novel information about canine hemoplasmas with relevance in distribution, transmission routes, and cross-species transmission.

Browsing by Author "Vianna, Juliana"

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