PDF(Pubmed)
Abstract：
Maintenance metabolism as the minimum energy expenditure needed to maintain homeothermy (a high and stable body temperature, T b), reflects the magnitude of metabolic machinery and the associated costs of self-maintenance in endotherms (organisms able to produce heat endogenously). Therefore, it can interact with most, if not all, organismal functions, including the behavior-fitness linkage. Many endothermic animals can avoid the costs of maintaining homeothermy and temporally reduce T b and metabolism by entering heterothermic states like torpor, the most effective energy-saving strategy. Variations in BMR, behavior, and torpor use are considered to be shaped by food resources, but those conclusions are based on research studying these traits in isolation. We tested the effect of ecological contexts (food availability and predation risk) on the interplay between the maintenance costs of homeothermy, heterothermy, and exploration in a wild mammal-the yellow-necked mouse. We measured maintenance metabolism as basal metabolic rate (BMR) using respirometry, distance moved (exploration) in the open-field test, and variation in T b (heterothermy) during short-term fasting in animals captured at different locations of known natural food availability and predator presence, and with or without supplementary food resources. We found that in winter, heterothermy and exploration (but not BMR) negatively correlated with natural food availability (determined in autumn). Supplementary feeding increased mouse density, predation risk and finally had a positive effect on heterothermy (but not on BMR or exploration). The path analysis testing plausible causal relationships between the studied traits indicated that elevated predation risk increased heterothermy, which in turn negatively affected exploration, which positively correlated with BMR. Our study indicates that adaptive heterothermy is a compensation strategy for balancing the energy budget in endothermic animals experiencing low natural food availability. This study also suggests that under environmental challenges like increased predation risk, the use of an effective energy-saving strategy predicts behavioral expression better than self-maintenance costs under homeothermy.
摘要：
维持新陈代谢是维持稳态所需的最低能量消耗(高而稳定的体温，Tb),反映了代谢机制的规模以及在吸热（能够内生产生热量的生物体）中自我维持的相关成本。因此,它可以与大多数人互动，如果不是全部,有机功能，包括行为-健身联动。许多吸热动物可以避免维持稳态的成本，并通过进入像torpor这样的异热状态来暂时减少Tb和新陈代谢，最有效的节能策略。BMR的变化，行为，和火种的使用被认为是由食物资源决定的，但是这些结论是基于孤立研究这些特征的研究。我们测试了生态环境（食物供应和捕食风险）对家庭维持成本之间相互作用的影响，异形,在一只野生哺乳动物——黄颈老鼠中进行探索。我们使用呼吸测量法将维持代谢测量为基础代谢率（BMR），在野外测试中移动距离(勘探)，以及在已知天然食物供应和捕食者存在的不同位置捕获的动物在短期禁食期间的Tb（异质）变化，有或没有补充食物资源。我们发现在冬天,异质和探索（而不是BMR）与天然食物供应呈负相关（在秋季确定）。补充喂养增加小鼠密度，捕食风险，并最终对异热有积极影响(但对BMR或探索没有影响)。路径分析测试了所研究特征之间的合理因果关系，表明捕食风险升高会增加异质性，这反过来又对探索产生了负面影响，与BMR呈正相关。我们的研究表明，适应性异质热是一种补偿策略，用于平衡经历低自然食物供应的吸热动物的能量预算。这项研究还表明，在捕食风险增加等环境挑战下，在恒温线下，使用有效的节能策略比自我维护成本更好地预测行为表达。
