Centro Tlaxcala de Biología de la Conducta, Universidad Autónoma de Tlaxcala, Carretera Tlaxcala-Puebla km 1.5, 90062, Tlaxcala, Mexico.
Facultad de Ciencias, Universidad Nacional Autónoma de México, Circuito exterior s/n, Ciudad Universitaria, Coyoacán, 04510, Mexico City, Mexico.
J Comp Physiol B. 2022 Sep;192(5):659-668. doi: 10.1007/s00360-022-01448-3. Epub 2022 Jul 18.
Body maintenance costs are often considered a proxy for performance in fitness traits. Maintenance energy requirements are measured as minimal metabolic rate of inactive, postabsorptive individuals in the laboratory. For mountain-dwelling species, translocation to the laboratory often means that they are also moved to another elevation. Due to physiological adaptations to local oxygen pressure, rapid elevational change can alter metabolic rate and translocation may result in erroneous estimates of body maintenance costs. In this study, we measured resting metabolic rate (RMR) of three populations of the Mesquite lizard (Sceloporus grammicus, Wiegmann 1828) at their native elevations (i.e., 2600, 3200 and 4100 m). Our results showed that at native elevations, mass specific RMR of lizards from the high elevation population (4100 m) did not differ from the RMR of the other populations (i.e., 2600 and 3200 m), whereas the lizards from the low elevation (2600 m) had lower RMR than those from the intermediate population. These results differ from a previous study in which the RMR of lizards from the same populations were reported to increase with native elevation when translocated and measured at an intermediate elevation. Hence, our results show that translocation in elevation can affect metabolic measures. We caution researchers that changes in elevation may preclude accurate measures of RMR in some animals and may therefore incorrectly predict performance of fitness-related traits.
身体维持成本通常被认为是适应能力的一个指标。维持能量需求是通过实验室中处于非活动、吸收后状态的个体的最小代谢率来测量的。对于居住在山区的物种来说，将它们转移到实验室通常意味着它们也被转移到了另一个海拔高度。由于对当地气压的生理适应，快速的海拔变化会改变代谢率，而转移可能会导致对身体维持成本的错误估计。在这项研究中，我们测量了三种Mesquite 蜥蜴（Sceloporus grammicus，Wiegmann 1828）种群在其原生海拔高度（即 2600、3200 和 4100 米）的静息代谢率（RMR）。我们的结果表明，在原生海拔高度，来自高海拔种群（4100 米）的蜥蜴的比质量代谢率与其他种群（即 2600 和 3200 米）的代谢率没有差异，而来自低海拔（2600 米）的蜥蜴的代谢率则低于中间种群的蜥蜴。这些结果与之前的一项研究不同，该研究报告称，当同一种群的蜥蜴在海拔高度居中的地方被转移并测量时，它们的 RMR 会随着原生海拔的升高而升高。因此，我们的结果表明，海拔高度的转移会影响代谢测量。我们提醒研究人员，海拔高度的变化可能会使一些动物的 RMR 测量不准确，从而错误地预测与适应能力相关的特征的表现。
