Metabolic rate and prehibernation fattening in free-living arctic ground squirrels
| Autor: | Brian M. Barnes, C. Loren Buck, Michael J. Sheriff, Øivind Tøien, Robert W. Fridinger |
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| Rok vydání: | 2013 |
| Předmět: |
Male
Time Factors Adult male Physiology Foraging Biology Weight Gain Biochemistry Animal science Oxygen Consumption Hibernation medicine Animals Ecology Sciuridae Total body Arctic Basal metabolic rate Metabolic rate Lean body mass Body Composition Animal Science and Zoology Female Seasons medicine.symptom Energy Metabolism Weight gain Body Temperature Regulation |
| Zdroj: | Physiological and biochemical zoology : PBZ. 86(5) |
| ISSN: | 1537-5293 |
| Popis: | Hibernating mammals become sequestered and cease foraging during prolonged seasonal periods of reduced or unpredictable food availability and instead rely on cached food and/or endogenous reserves of fat and protein accumulated during the previous active season. The gain in weight is due to increased food consumption, but it also has been hypothesized that hibernators maximize rates of fattening by decreasing costs of maintenance before weight gain, reflected in reduced resting metabolic rate (RMR). We recorded repeated measures of total body, lean, and fat mass in individual adult male and female arctic ground squirrels across their active season and found that squirrels increased body mass by 42% (males) and 62% (females). This gain was achieved through a 17% increase in lean mass and a 7-8-fold increase in fat mass; however, mass gain was not linear and patterns differed between sexes. Contrary to our hypothesis, decreases in RMR were not associated with rapid mass gain. We found RMR of males increased (whole-animal RMR or lean-mass-specific RMR) or remained constant (mass-specific RMR) for most of the active season and decreased only after the majority of mass had been gained. In females, although RMR (whole-animal, mass-specific, and lean-mass RMR) generally decreased across the active season, the greatest decrease occurred late in the active season after the majority of mass had been gained. In conclusion, arctic ground squirrels do not trade off metabolism to facilitate rates of weight gain before hibernation, but they do use energy sparing strategies before hibernation that help maintain peak mass. |
| Databáze: | OpenAIRE |
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