Browsing by Author "Barcelo, Gonzalo"

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    Body mass, phylogeny and diet composition affects kidney morphology in passerine birds
    (2012) Barcelo, Gonzalo; Salinas, Jonathan; Sabat, Pablo
    We studied the renal morphology of 16 species of passerines to assess whether the composition of the diet of birds have been paralleled by differences in the characteristics of the kidneys. We determined the number and length of the medullary cones and the percentage of renal medulla in birds with contrasting dietary habits and then correlated these features with the percentage of nitrogen and proportion of invertebrates in the diet. To examine the correlation between kidney and diet variables, we first used standard correlation and least square regression, and correlation and regression on phylogenetically independent data. We found that the mass of the medullary portion of the kidney, and the medullary cone length were negatively correlated with the percentage of invertebrates present in the diet. We hypothesized that the further development of the renal medulla observed in granivorous birds may be correlated with the small amount of water present in the seeds. Our results suggest that the availability of water in different foods is probably one of the main factors that have led to structural and probably functional changes of the kidney in the studied species. J. Morphol., 2012. (C) 2012 Wiley Periodicals, Inc.
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    Energetic costs and implications of the intake of plant secondary metabolites on digestive and renal morphology in two austral passerines
    (2016) Barcelo, Gonzalo; Manuel Rios, Juan; Maldonado, Karin; Sabat, Pablo
    Seed-eating birds have a diet of high nutritional value; however, they must cope with plant secondary metabolites (PSM). We postulated that the detoxification capacity of birds is associated with a metabolic cost, given that the organs responsible for detoxification significantly contribute to energetic metabolism. We used an experimental approach to assess the effects of phenol-enriched diets on two passerines with different feeding habits: the omnivorous rufous-collared sparrow (Zonotrichia capensis) and the granivorous common diuca-finch (Diuca diuca). The birds were fed with one of three diets: control diet, supplemented with tannic acid, or supplemented with Opuntia ficus-indica phenolic extract (a common food of the sparrow but not the finch). After 5 weeks of exposure to the diets, we measured basal metabolic rates (BMR), energy intake, glucuronic acid output and digestive and kidney structure. In both species, detoxification capacity expressed as glucuronic acid output was higher in individuals consuming phenol-enriched diets compared to the control diet. However, whereas sparrows increase energy intake and intestinal mass when feeding on phenol-enriched diets, finches had lower intestinal mass and energy intake remains stable. Furthermore, sparrows had higher BMR on phenolenriched diets compared to the control group, whereas in the finches BMR remains unchanged. Interspecific differences in response to phenols intake may be determined by the dietary habits of these species. While both species can feed on moderate phenolic diets for 5 weeks, energy costs may differ due to different responses in food intake and organ structure to counteract the effects of PSM intake.
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    New media and the digitized paranormal: instrumentation, affective atmospheres, and the production of history in Chile
    (WILEY, 2021) Espirito Santo, Diana; Barcelo, Gonzalo
    In the last decade in Chile, an increasing amount of paranormal investigation companies have carried out ghost tours in patrimonial and historical places, using diverse technologies to penetrate into the history of sites. We ethnographically and analytically explore two related questions. First, we ask what paranormal instrumentation does to collective memory and to history. We argue that these 'registers' of the paranormal create 'affective atmospheres', namely from the forms of indeterminacy embedded in the functioning and performance of the apparatuses. Our argument is that these machines are mechanisms for the creation of a new history, one that is apprehended affectively. Second, in the context of an explosion of adherence in Chile to forms of new media, we employ the notion of `dark media' to illustrate that online material posted by paranormal researchers appears to escape any form of mediational understanding, feeding at once the public's perceptive and affective dispositions.
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    Temporal variation in isotopic composition of Pygoscelis penguins at Ardley Island, Antarctic: Are foraging habits impacted by environmental change?
    (2017) Negrete, Pablo; Sallaberry, Michel; Barcelo, Gonzalo; Maldonado, Karin; Perona, Franco; McGill, Rona A. R.; Quillfeldt, Petra; Sabat, Pablo
    Several studies have suggested that penguins are undergoing a major restructuring of their feeding habits and distribution after drastic climatic changes in the Antarctic Peninsula region. With the objective of estimating potential medium-term and inter-annual variations in trophic niche, we measured delta N-15 and delta C-13 in feather samples of pygoscelid penguins from museum specimens (1982-1984) and in blood and feather samples from 2009/10-2011 collected from animals on Ardley Island. Current penguin feathers had lower delta C-13 and delta N-15 values and were more similar to Antarctic krill values, than feathers in 1982-1984 and blood from 2009/10-2011. Moreover, delta C-13 and delta N-15 values from museum feathers and modern samples occupied a larger isotopic space in Gentoo Penguins (Pygoscelis papua), compared to Ad,lie Penguins (Pygoscelis adeliae) and Chinstrap Penguins (Pygoscelis antarctica). Our results from feathers samples indicated that penguins have decreased their consumption of fish and other prey of higher trophic levels in the early interbreeding period (EIBP), while increasing the amount of euphausiids (Antarctic krill Euphausia superba) taken. The isotopic values of the species suggest that foraging sites varied significantly over time and seasonally. We suggest that environmental changes may have modified the feeding habits of pygoscelid penguins, resulting in changed foraging behaviour in the EIBP, and altering the secondary prey consumption. Prey choice in breeding pygoscelid species is probably limited by the foraging range around the breeding colony and competitive exclusion between congeners.
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    Thermal history can affect the short-term thermal acclimation of basal metabolic rate in the passerine Zonotrichia capensis
    (2009) Barcelo, Gonzalo; Salinas, Jonathan; Cavieres, Grisel; Canals, Mauricio; Sabat, Pablo
    The obligatory cost of living for endotherms is measured by basal metabolic rate (BMR), a variable that is known to change after thermal acclimation. However, the relative timing between variation in ambient temperature and BMR is not well understood. in this study, we addressed this problem in the sparrow Zonotrichia capensis, studying whether previous thermal history affects the response of BMR to a new acclimation temperature. We found that after 4 weeks of acclimation either to 30 or 15 degrees C birds exhibited significant differences in BMR from pre-acclimation levels. Nevertheless, after a re-acclimation to the opposite treatment for six additional weeks, in the group previously acclimated to warm conditions the change in BMR was significantly greater than in the group previously acclimated to cold. We also found differences in the mass of the small intestine between groups but constancy in the mass of liver, kidney and heart masses at the end of the experiments. Our results indicate that the thermal history affects metabolic adjustments and highlights the importance of considering this when evaluating the plasticity of metabolic traits in small birds. (C) 2009 Elsevier Ltd. All rights reserved.