Voluntary running in deer mice: speed, distance, energy costs and temperature effects
Voluntary running in deer mice: speed, distance, energy costs and temperature effects
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DOI：
10.1242/jeb.01213
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发表时间：
2004-10-01
影响因子：
2.8
通讯作者：
Gomes, FR
中科院分区：
文献类型：
--
作者：
Chappell, MA;Garland, T;Gomes, FR
生态学家和生理学家对陆地运动的能量学非常感兴趣，但我们目前几乎所有的知识都来自于动物的强迫运动。为了探索自愿运动过程中的能量使用和行为模式，我们开发了一种方法，可以在几天的时间内以高时间分辨率几乎连续测量自由行为的小型哺乳动物的代谢率。我们使用这种方法来研究环境温度（T（a）），运动行为和能量消耗之间的关系，鹿鼠，一种小型哺乳动物，经常遇到大范围的温度在其自然栖息地。我们测试了跑步行为和代谢特征的个体一致性，并确定了运动成本如何随速度和T（a）而变化。由于小型哺乳动物的体温调节成本的重要性，我们检查了在T（a），低于热中性区的运动热量替代的热量产生，并确定了每日能量预算的比例，包括运动costs.Locomotor行为是高度可变的个体之间，但有很高的可重复性，至少在很短的时间间隔。我们发现，在速度或距离跑中几乎没有与温度相关的变化，但T（a）强烈影响能量成本。在低T（a）时，运动热部分替代产热。这使低温运行期间的能源消耗减少了23- 37%，但运行成本只占能源预算的一小部分，因此通过替代能源节省的每日能源要少得多。鹿鼠并没有调整奔跑速度来最大化代谢经济，因为它们很少使用提供最低运输成本的高速。最高自主速度（4-5 km h（-1））几乎总是低于预测的最大有氧速度，并且远低于该物种的最大短跑速度。最大自主达到的耗氧率（V（O2））最高的低T（a），但很少接近最大V（O2）在强制跑台运动。与最大自主V（O2）一致的平均呼吸交换率随T（a）下降而略有增加，但始终低于1.0（另一个表明代谢率低于有氧最大值的指标）。具有高跑步表现（累积距离和跑步时间）的个体具有高静息代谢，这表明具有高活动能力或倾向的成本。
The energetics of terrestrial locomotion are of considerable interest to ecologists and physiologists, but nearly all of our current knowledge comes from animals undergoing forced exercise. To explore patterns of energy use and behavior during voluntary exercise, we developed methods allowing nearly continuous measurements of metabolic rates in freely behaving small mammals, with high temporal resolution over periods of several days. We used this approach to examine relationships between ambient temperature (T(a)), locomotor behavior and energy costs in the deer mouse, a small mammal that routinely encounters a large range of temperatures in its natural habitat. We tested for individual consistency in running behavior and metabolic traits, and determined how locomotor costs vary with speed and T(a). Because of the importance of thermoregulatory costs in small mammals, we checked for substitution of exercise heat for thermostatic heat production at T(a), below the thermal neutral zone and determined the fraction of the daily energy budget comprising exercise costs.Locomotor behavior was highly variable among individuals but had high repeatability, at least over short intervals. We found few temperature-related changes in speed or distance run, but T(a) strongly affected energy costs. Partial substitution of exercise heat for thermogenic heat occurred at low T(a). This reduced energy expenditure during low-temperature running by 23-37%, but running costs comprised a fairly minor fraction of the energy budget, so the daily energy savings via substitution were much smaller. Deer mice did not adjust running speed to maximize metabolic economy, as they seldom used the high speeds that provide the lowest cost of transport. The highest voluntary speeds (4-5 km h(-1)) were almost always below the predicted maximal aerobic speed, and were much less than the species' maximal sprint speed. Maximum voluntarily attained rates of oxygen consumption (V(O2)) were highest at low T(a), but rarely approached maximal V(O2) during forced treadmill exercise. Mean respiratory exchange ratios coincident with maximal voluntary V(O2) increased slightly as T(a) declined, but were always below 1.0 (another indication that metabolic rate was less than the aerobic maximum). Individuals with high running performance (cumulative distance and running time) had high resting metabolism, which suggests a cost of having high capacity or propensity for activity.