Browsing by Author "Veloso, Claudio"

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    Effect of Food Quality on the Energetics of Reproduction in a Precocial Rodent, Octodon Degus
    (2000) Veloso, Claudio; Bozinovic Kuscevic, Francisco
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    Gut size variation among Bufo spinulosus populations along an altitudinal (and dietary) gradient
    (2009) Naya, Daniel E.; Veloso, Claudio; Bozinovic, Francisco
    To date, digestive flexibility has been studied in dozens of vertebrate species. However, practically all of these works has ignored the importance of intraspecific physiological variability across populations inhabiting different habitats. Here, we compare the digestive tract gross morphology of three populations of the Andean toad (Bufo spinulosus), inhabiting along an altitudinal gradient and feeding on different food items. Results support a core prediction of digestive theory, i.e., intestinal length increases in parallel with the content of indigestible material in the natural diet. The present study suggest how variation in the abiotic environment associated with altitude (e.g., temperature, water availability, soil quality) can change biotic conditions (e.g., vegetation cover, prey availability), affect feeding behavior of individuals (e.g., width and composition of trophic niche), and, ultimately, individuals' digestive features (e.g., gut morphology).
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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.