Browsing by Author "Clavijo Baquet, Sabrina"

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    Increasing Winter Maximal Metabolic Rate Improves Intrawinter Survival in Small Birds
    (UNIV CHICAGO PRESS, 2017) Petit, Magali; Clavijo Baquet, Sabrina; Vezina, Francois
    Small resident bird species living at northern latitudes increase their metabolism in winter, and this is widely assumed to improve their chances of survival. However, the relationship between winter metabolic performance and survival has yet to be demonstrated. Using capture-mark-recapture, we followed a population of free-living black-capped chickadees (Poecile atricapillus) over 3 yr and evaluated their survival probability within and among winters. We also measured the size-independent body mass (M-s), hematocrit (Hct), basal metabolic rate (BMR), and maximal thermogenic capacity (Msum) and investigated how these parameters influenced survival within and among winters. Results showed that survival probability was high and constant both within (0.92) and among (0.96) winters. They also showed that while M-s, Hct, and BMR had no significant influence, survival was positively related to Msumfollowing a sigmoid relationshipwithin but not among winter. Birds expressing an Msum below 1.26 W (i.e., similar to summer levels) had a <50% chance of survival, while birds with an Msum above 1.35 W had at least a 90% chance of surviving through the winter. Our data therefore suggest that black-capped chickadees that are either too slow or unable to adjust their phenotype from summer to winter have little chances of survival and thus that seasonal upregulation of metabolic performance is highly beneficial. This study is the first to document in an avian system the relationship between thermogenic capacity and winter survival, a proxy of fitness.
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    Resting Metabolic Rate Is Positively Correlated with Parental Care Behavior in a Dwarf Hamster
    (2016) Clavijo Baquet, Sabrina; Cumplido, Nicolás; Bozinovic Kuscevic, Francisco
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    The Mean and Variance of Environmental Temperature Interact to Determine Physiological Tolerance and Fitness
    (UNIV CHICAGO PRESS, 2011) Bozinovic, Francisco; Bastias, Daniel A.; Boher, Francisca; Clavijo Baquet, Sabrina; Estay, Sergio A.; Angilletta, Michael J., Jr.
    Global climate change poses one of the greatest threats to biodiversity. Most analyses of the potential biological impacts have focused on changes in mean temperature, but changes in thermal variance will also impact organisms and populations. We assessed the combined effects of the mean and variance of temperature on thermal tolerances, organismal survival, and population growth in Drosophila melanogaster. Because the performance of ectotherms relates nonlinearly to temperature, we predicted that responses to thermal variation (+/-0 degrees or +/-5 degrees C) would depend on the mean temperature (17 degrees or 24 degrees C). Consistent with our prediction, thermal variation enhanced the rate of population growth (r(max)) at a low mean temperature but depressed this rate at a high mean temperature. The interactive effect on fitness occurred despite the fact that flies improved their heat and cold tolerances through acclimation to thermal conditions. Flies exposed to a high mean and a high variance of temperature recovered from heat coma faster and survived heat exposure better than did flies that developed at other conditions. Relatively high survival following heat exposure was associated with low survival following cold exposure. Recovery from chill coma was affected primarily by the mean temperature; flies acclimated to a low mean temperature recovered much faster than did flies acclimated to a high mean temperature. To develop more realistic predictions about the biological impacts of climate change, one must consider the interactions between the mean environmental temperature and the variance of environmental temperature.