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《Current Zoology》 2010年06期
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Sources and significance of variation in basal,summit and maximal metabolic rates in birds

Andrew E. MCKECHNIE  David L. SWANSON  
【摘要】:正 The rates at which birds use energy may have profound effects on fitness, thereby influencing physiology, behavior,ecology and evolution. Comparisons of standardized metabolic rates (e.g., lower and upper limits of metabolic power output)present a method for elucidating the effects of ecological and evolutionary factors on the interface between physiology and lifehistory in birds. In this paper we review variation in avian metabolic rates [basal metabolic rate (BMR; minimum normothermicmetabolic rate), summit metabolic rate (M_(sum); maximal thermoregulatory metabolic rate), and maximal metabolic rate (MMR;maximal exercise metabolic rate)], the factors associated with this variation, the evidence for functional links between thesemetabolic traits, and the ecological and evolutionary significance of avian metabolic diversity. Both lower and upper limits tometabolic power production are phenotypically flexible traits, and vary in association with numerous ecological and evolutionaryfactors. For both inter- and intraspecific comparisons, lower and upper limits to metabolic power production are generallyupregulated in response to energetically demanding conditions and downregulated when energetic demands are relaxed, or underconditions of energetic scarcity. Positive correlations have been documented between BMR, M_(sum) and MMR in some, but not allstudies on birds, providing partial support for the idea of a functional link between lower and upper limits to metabolic powerproduction, but more intraspecific studies are needed to determine the robustness of this conclusion. Correlations between BMRand field metabolic rate (or daily energy expenditure) in birds are variable, suggesting that the linkage between these traits is subjectto behavioral adjustment, and studies of the relationship between field and maximal metabolic rates are lacking. Our understandingof avian metabolic diversity would benefit from future studies of: (1) the functional and mechanistic links between lowerand upper limits of metabolic power output; (2) the environmental and ecological cues driving phenotypically flexible metabolicresponses, and how responses to such cues might impact population responses to climate change; (3) the shapes of metabolic reactionnorms and their association with environmental variability; and (4) the relationship of metabolic variation to fitness, includingstudies of repeatability and heritability of minimum and maximum metabolic power output

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