Data from: Differential effects of food availability on minimum and maximum rates of metabolism

Metabolic rates reflect the energetic cost of living but exhibit remarkable variation among conspecifics, partly as a result of the constraints imposed by environmental conditions. Metabolic rates are sensitive to changes in temperature and oxygen availability, but effects of food availability, particularly on maximum metabolic rates, are not well understood. Here, we show in brown trout (Salmo trutta) that maximum metabolic rates are immutable but minimum metabolic rates increase as a positive function of food availability. As a result, aerobic scope (i.e. the capacity to elevate metabolism above baseline requirements) declines as food availability increases. These differential changes in metabolic rates likely have important consequences for how organisms partition available metabolic power to different functions under the constraints imposed by food availability.

代谢率体现了生物体生存的能量消耗成本，但同种个体间的代谢率存在显著差异，这在一定程度上由环境条件施加的约束所导致。代谢率对温度与氧可利用性的变化极为敏感，但食物可获得性的影响——尤其是对最大代谢率的影响——目前尚未得到充分阐明。本研究以褐鳟（Salmo trutta）为实验材料，证实其最大代谢率恒定不变，而最小代谢率随食物可获得性的提升呈正相关增长。由此，有氧代谢范围（aerobic scope）——即代谢率提升至基础代谢需求以上的能力——随食物可获得性的增加而降低。代谢率的这类差异化变化，可能对生物体在食物可获得性施加的约束条件下，如何将可用代谢能量分配至不同生理功能产生重要影响。