Browsing by Author "Barroso, Omar"

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    Associations among MHC genes, latitude, and avian malaria infections in the rufous-collared sparrow (Zonotrichia capensis)
    (2024) de Aguilar, Juan Rivero; Barroso, Omar; Bonaccorso, Elisa; Cadena, Hector; Hussing, Lucas; Jorquera, Josefina; Martinez, Javier; Martinez-de la Puente, Josue; Marzal, Alfonso; Miranda, Fabiola Leon; Merino, Santiago; Matta, Nubia E.; Ramenofsky, Marilyn; Rozzi, Ricardo; Valeris-Chacin, Carlos E.; Vasquez, Rodrigo A.; Vianna, Juliana A.; Wingfield, John C.
    The major histocompatibility complex (MHC) is a genetic region in jawed vertebrates that contains key genes involved in the immune response. Associations between the MHC and avian malaria infections in wild birds have been observed and mainly explored in the Northern Hemisphere, while a general lack of information remains in the Southern Hemisphere. Here, we investigated the associations between the MHC genes and infections with Plasmodium and Haemoproteus blood parasites along a latitudinal gradient in South America. We sampled 93 rufous-collared sparrows (Zonotrichia capensis) individuals from four countries, Colombia, Ecuador, Peru, and Chile, and estimated MHC-I and MHC-II allele diversity. We detected between 1-4 (MHC-I) and 1-6 (MHC-II) amino acidic alleles per individual, with signs of positive selection. We obtained generalized additive mixed models to explore the associations between MHC-I and MHC-II diversity and latitude. We also explored the relationship between infection status and latitude/biome. We found a non-linear association between the MHC-II amino acidic allele diversity and latitude. Individuals from north Chile presented a lower MHC genetic diversity than those from other locations. We also found an association between deserts and xeric shrublands and a lower prevalence of Haemoproteus parasites. Our results support a lower MHC genetic in arid or semi-arid habitats in the region with the lower prevalence of Haemoproteus parasites.
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    Morphological description of the White-throated treerunner (Pygarrhichas albogularis, King 1831) in the Cape Horn Biosphere Reserve, Chile
    (2024) Novoa Galaz, Fernando Javier; Jara Millar, Rocio; Barroso, Omar; Altamirano Oyarzun, Tomas Alberto; Ibarra Eliessetch, José Tomas; Rivero De Aguilar, Juan; Vasquez, Rodrigo A.; Rozzi, Ricardo
    La ecorregión subantártica de Magallanes constituye una de las áreas silvestres más prístinas y alberga los ecosistemas boscosos más australes del mundo, que están protegidos por la Reserva de la Biosfera Cabo de Hornos (RBCH), Chile. En estos bosques, las aves son el grupo de vertebrados con mayor número de especies. Sin embargo, aspectos esenciales de la ecología y la morfología de varias especies de esta región todavía han sido poco investigados. Entre estas especies, se incluye el comesebo grande (Pygarrhichas albogularis, King 1831), considerado un “fósil viviente” por ser la única especie viva del género Pygarrhichas. Además, es un furnariido endémico de los bosques templados de Sudamérica. Utilizando la base de datos de 23 años del Programa de Investigación Ornitológica a Largo Plazo del Parque Omora (54º56’S, 67º38’W), que ha realizado capturas y anillamientos de aves de bosque, describimos la morfología, longevidad y presencia del comesebo grande en la RBCH. Entre los años 2000 y 2022 se anillaron 91 individuos, incluyendo 29 recapturas que nos permitieron determinar que esta especie puede vivir al menos cinco años. Las medidas morfométricas mostraron una correlación positiva entre las medidas de pico y la longitud del tarso con las longitudes de la cola y del ala. El peso varió en cada estación anual, pero no significativamente. La mayor presencia al interior del bosque antiguo sugiere una dependencia de esta especie con los grandes árboles. Este estudio amplía el conocimiento sobre la historia natural del comesebo grande, particularmente de sus poblaciones que habitan en los bosques más australes del mundo.
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    Survival rates in the world's southernmost forest bird community
    (2023) Sandvig, Erik M.; Quilodran, Claudio S.; Altamirano, Tomas A.; Aguirre, Francisco; Barroso, Omar; de Aguilar, Juan Rivero; Schaub, Michael; Kery, Marc; Vasquez, Rodrigo A.; Rozzi, Ricardo
    The Magellanic sub-Antarctic Forest is home to the world's southernmost avian community and is the only Southern Hemisphere analogue to Northern Hemisphere temperate forests at this latitude. This region is considered among the few remaining pristine areas of the world, and shifts in environmental conditions are predominantly driven by climate variability. Thus, understanding climate-driven demographic processes is critical for addressing conservation issues in this system under future climate change scenarios. Here, we describe annual survival patterns and their association with climate variables using a 20-year mark-recapture data set of five forest bird species in the Cape Horn Biosphere Reserve. We develop a multispecies hierarchical survival model to jointly explore age-dependent survival probabilities at the community and species levels in a group of five forest passerines. At the community level, we assess the association of migratory behavior and body size with survival, and at the species level, we investigate the influence of local and regional climatic variables on temporal variations of survival. We found a positive effect of precipitation and a negative effect of El Nino Southern Oscillation on juvenile survival in the white-crested Elaenia and a consistent but uncertain negative effect of temperature on survival in juveniles and 80% of adults. We found only a weak association of climate variables with survival across species in the community and no temporal trends in survival for any of the species in either age class, highlighting apparent stability in these high austral latitude forests. Finally, our findings provide an important resource of survival probabilities, a necessary input for assessing potential impacts of global climate change in this unique region of the world.