Browsing by Author "Vianna, Juliana"
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- ItemChinstrap 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
- ItemCryptic 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
- ItemDiagnóstico 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 ForestalConscientes 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.
- ItemIs 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 ForestalLa 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.
- ItemLandscape 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.
- ItemPhylogeography of the Marine Otter (Lontra felina): Historical and Contemporary Factors Determining Its Distribution(2010) Vianna, Juliana; Ayerdi Retamales, Paula Andrea.; Faugeron, Sylvain Wielfrid
- ItemSpatial 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, JulianaAbstract 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.
- ItemWidespread 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, JavierBlood 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.