Browsing by Author "Canals, Mauricio"

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    Chile Confronts its Environmental Health Future After 25 Years of Accelerated Growth
    (2015) Pino, Paulina; Iglesias, Veronica; Garreaud, Rene; Cortés Arancibia, Sandra; Canals, Mauricio
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    Interplay between the morphometry of the lungs and the mode of locomotion in birds and mammals
    (2007) Figueroa, Daniela; Olivares, Ricardo; Salaberry, Michel; Sabat, Pablo; Canals, Mauricio
    We studied the lung diffusion parameters of two species of birds and two species-of mammals to explore how structural and functional features may be paralleled by differences in life style or phylogenetic origin. We used two fast-flying species (one mammal and one bird), one running mammal and one bird species that flies only occasionally as models. The harmonic mean thickness of the air-blood barrier was very thin in the species we studied. An exception was the Chilean tinamou Notoprocta perdicaria, which only flies occasionally. It showed an air-blood barrier as thick as that of flightless Galliformes. We found that the respiratory surface density was significantly greater in flying species compared to running species. The estimated values for the oxygen diffusion capacity, 13,02 follow the same pattern: the highest values were obtained in the flying species, the bat and the eared dove. The lowest value was in N. perdicaria. Our findings suggest that the studied species show refinements in their morphometric lung parameters commensurate to their energetic requirements as dictated by their mode of locomotion, rather than their phylogenetic origin. The air-blood barrier appears to be thin in most birds and small mammals, except those with low energetic requirements such as the Chilean tinamou. In the species we studied, the respiratory surface density appears to be the factor most responsive to the energetic requirements of flight.
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    Physiological responses in rufous-collared sparrows to thermal acclimation and seasonal acclimatization
    (2009) Maldonado, Karin Evelyn; Cavieres, Grisel; Veloso, Claudio; Canals, Mauricio; Sabat, Pablo
    A large number of physiological acclimation studies assume that flexibility in a certain trait is both adaptive and functionally important for organisms in their natural environment; however, it is not clear how an organism's capacity for temperature acclimation translates to the seasonal acclimatization that these organisms must accomplish. To elucidate this relationship, we measured BMR and TEWL rates in both field-acclimatized and laboratory-acclimated adult rufous-collared sparrows (Zonotrichia capensis). Measurements in field-acclimatized birds were taken during the winter and summer seasons; in the laboratory-acclimated birds, we took our measurements following 4 weeks at either 15 or 30A degrees C. Although BMR and TEWL rates did not differ between winter and summer in the field-acclimatized birds, laboratory-acclimated birds exposed to 15A degrees C exhibited both a higher BMR and TEWL rate when compared to the birds acclimated to 30A degrees C and the field-acclimatized birds. Because organ masses seem to be similar between field and cold-acclimated birds whereas BMR is higher in cold-acclimated birds, the variability in BMR cannot be explained completely by adjustments in organ masses. Our findings suggest that, although rufous-collared sparrows can exhibit thermal acclimation of physiological traits, sparrows do not use this capacity to cope with minor to moderate fluctuations in environmental conditions. Our data support the hypothesis that physiological flexibility in energetic traits is a common feature of avian metabolism.
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    Temperature variability and thermal performance in ectotherms : acclimation, behaviour, and experimental considerations
    (2016) Bozinovic Kuscevic, Francisco; Sabat, Pablo; Rezende Landaeta, Enrico; Canals, Mauricio
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    Temperature variability and thermal performance in ectotherms: acclimation, behaviour, and experimental considerations
    (2016) Bozinovic, Francisco; Sabat, Pablo; Rezende, Enrico L.; Canals, Mauricio
    Background: Among the predictions of the effect of future climate change, the impact of thermal conditions at local levels on the performance of individuals and their acclimation capacities is key to understanding animals' responses to global warming. Woodlice (the terrestrial isopod Porcellio laevis) exhibit a readily observed behaviour that may reflect their acclimation capacities. When they find themselves on their back, they sometimes roll over (i.e. right themselves). Whether they do, and how fast they do it, are measures of their behaviour and performance that vary with ambient temperature.
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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.
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    Water and energy economy of an omnivorous bird
    (2006) Sabat, Pablo; Cavieres, Grisel; Veloso, Claudio; Canals, Mauricio
    We investigated the intraspecific variation in basal metabolic rate (BMR) and total evaporative water loss (TEWL) in the omnivorous passerine Zonotrichia capensis from two populations inhabiting regions with different precipitation regimes and aridity indices. Values of TEWL in birds from the semi-arid region were significantly lower than those found in sparrows from the mesic region. TEWL in birds from the semi-arid site was 74% of the expectation based on body mass for passerines from mesic areas and similar to the allometric expectation for passerines from and environments. In sparrows from the mesic area, TEWL was higher than predicted by their body mass for passerines from and environments (133%), but very close (97%) to the expectation for passerines from mesic areas. BMR values were 25% lower in sparrows from the semi-arid region. The lower TEWL and BMR of birds from the semi-arid region may be a physiological adjustment that allows them to cope with fewer resources and/or water. We propose that the lower endogenous heat production in birds from the semi-arid environment may decrease their water requirements. (c) 2006 Elsevier Inc. All rights reserved.