Rezende Enrico L, Gomes Fernando R, Chappell Mark A, Garland Theodore
Department of Biology, University of California, Riverside, California 92521, USA.
Physiol Biochem Zool. 2009 Nov-Dec;82(6):662-79. doi: 10.1086/605917.
Locomotion is central to behavior and intrinsic to many fitness-critical activities (e.g., migration, foraging), and it competes with other life-history components for energy. However, detailed analyses of how changes in locomotor activity and running behavior affect energy budgets are scarce. We quantified these effects in four replicate lines of house mice that have been selectively bred for high voluntary wheel running (S lines) and in their four nonselected control lines (C lines). We monitored wheel speeds and oxygen consumption for 24-48 h to determine daily energy expenditure (DEE), resting metabolic rate (RMR), locomotor costs, and running behavior (bout characteristics). Daily running distances increased roughly 50%-90% in S lines in response to selection. After we controlled for body mass effects, selection resulted in a 23% increase in DEE in males and a 6% increase in females. Total activity costs (DEE - RMR) accounted for 50%-60% of DEE in both S and C lines and were 29% higher in S males and 5% higher in S females compared with their C counterparts. Energetic costs of increased daily running distances differed between sexes because S females evolved higher running distances by running faster with little change in time spent running, while S males also spent 40% more time running than C males. This increase in time spent running impinged on high energy costs because the majority of running costs stemmed from "postural costs" (the difference between RMR and the zero-speed intercept of the speed vs. metabolic rate relationship). No statistical differences in these traits were detected between S and C females, suggesting that large changes in locomotor behavior do not necessarily effect overall energy budgets. Running behavior also differed between sexes: within S lines, males ran with more but shorter bouts than females. Our results indicate that selection effects on energy budgets can differ dramatically between sexes and that energetic constraints in S males might partly explain the apparent selection limit for wheel running observed for over 15 generations.
运动是行为的核心，也是许多对适应性至关重要的活动（如迁徙、觅食）所固有的，并且它与其他生命史组成部分竞争能量。然而，关于运动活动和奔跑行为的变化如何影响能量预算的详细分析却很少见。我们在四个经过选择性培育以实现高自愿性轮转奔跑的家鼠品系（S系）及其四个非选择对照品系（C系）中对这些影响进行了量化。我们监测了24至48小时的轮转速度和氧气消耗，以确定每日能量消耗（DEE）、静息代谢率（RMR）、运动成本和奔跑行为（发作特征）。由于选择的结果，S系的每日奔跑距离增加了约50%至90%。在我们控制了体重影响后，选择导致雄性的DEE增加了23%，雌性增加了6%。总活动成本（DEE - RMR）在S系和C系中均占DEE的50%至60%，与C系的对应个体相比，S系雄性的总活动成本高29%，S系雌性高5%。每日奔跑距离增加的能量成本在性别上存在差异，因为S系雌性通过跑得更快而进化出更高的奔跑距离，奔跑时间变化不大，而S系雄性比C系雄性多花40%的时间奔跑。奔跑时间的增加导致了高能量成本，因为大部分奔跑成本源于“姿势成本”（RMR与速度与代谢率关系的零速度截距之间的差异）。在S系和C系雌性之间未检测到这些特征的统计学差异，这表明运动行为的巨大变化不一定会影响总体能量预算。性别之间的奔跑行为也存在差异：在S系中，雄性奔跑的次数更多但每次发作时间更短。我们的结果表明，对能量预算的选择效应在性别之间可能存在显著差异，并且S系雄性中的能量限制可能部分解释了超过15代以来观察到的轮转奔跑的明显选择极限。
