Ayala-Berdon Jorge, Medina-Bello Kevin I, Carballo-Morales Jorge D, Saldaña-Vázquez Romeo A, Villalobos Federico
SECIHTI, Universidad Autónoma de Tlaxcala, Carretera Tlaxcala-Puebla Km. 1.5, Tlaxcala C.P. 90062, Mexico.
Doctorado en Ciencias Biológicas, Centro Tlaxcala de Biología de la Conducta, Universidad Autónoma de Tlaxcala, Carretera Tlaxcala-Puebla Km. 1.5, Tlaxcala C.P. 90062, Mexico.
Zoology (Jena). 2025 May;170:126271. doi: 10.1016/j.zool.2025.126271. Epub 2025 May 8.
Thermal energetics define the way animals spend energy for thermoregulation. In this regard, numerous studies have determined that body mass (M) is the most influential morphological trait affecting the thermal traits in different species of birds and mammals. However, most of the studies have been focused on the basal metabolic rate (BMR), while other thermal traits have been less studied. We addressed this gap by examining thermal variables on bats of the family Vespertilionidae. Using open-flow respirometry, we measured BMR, absolute thermal conductance (C'), lower and upper critical temperatures (T and T), and breadth of the thermoneutral zone (TNZ) of 16 bat species ranging in M from ∼ 4.0-21.0 g from central Mexico. We: 1) combined our empirical data with information gathered from the literature and conducted phylogenetic analyses to investigate the relationship between M and thermal traits, 2) tested the relationship between mass independent C' and mass independent BMR with T and T of bats, and the relationship between critical temperatures and TNZ, and 3) mapped the thermal energetic traits along the phylogeny to explore their evolutionary trends. We found a positive relationship between M and BMR and absolute C' but not to T, T and TNZ of bats. Mass independent BMR and mass independent C' were positively related to T and T. Finally, T showed a negative relationship with TNZ while T exhibited a positive relationship with this thermal trait. The phylogenetic approach indicates that over the evolutionary history, BMR and C´ have decreased while T, T and TNZ have increased. Our results suggest that: 1) differences in the limits of the TNZ and C' may have helped bats to avoid the constraints on heat dissipation imposed by ambient temperatures, and 2) adaptive changes in M and thermal traits may have influenced the geographical distribution and energy-saving strategies of bats. These findings contribute to an understanding of how small endotherms cope with thermal challenges, shedding light on the physiological and evolutionary mechanisms that shape species' ecological niches and biogeographic patterns across diverse environments.
热能量学定义了动物用于体温调节的能量消耗方式。在这方面，大量研究已确定体重（M）是影响不同鸟类和哺乳动物热特性的最具影响力的形态特征。然而，大多数研究都集中在基础代谢率（BMR）上，而其他热特性的研究较少。我们通过研究蝙蝠科蝙蝠的热变量来填补这一空白。使用开放式流动呼吸测定法，我们测量了来自墨西哥中部的16种蝙蝠的基础代谢率、绝对热导率（C'）、下限和上限临界温度（Tₗ和Tₘ）以及热中性区（TNZ）的宽度，这些蝙蝠的体重范围约为4.0 - 21.0克。我们：1）将我们的实证数据与从文献中收集的信息相结合，并进行系统发育分析以研究体重与热特性之间的关系，2）测试了与体重无关的C'和与体重无关的BMR与蝙蝠的Tₗ和Tₘ之间的关系，以及临界温度与TNZ之间的关系，3）沿着系统发育图谱绘制热能量特性以探索它们的进化趋势。我们发现体重与基础代谢率和绝对C'之间存在正相关，但与蝙蝠的Tₗ、Tₘ和TNZ无关。与体重无关的基础代谢率和与体重无关的C'与Tₗ和Tₘ呈正相关。最后，Tₗ与TNZ呈负相关，而Tₘ与这一热特性呈正相关。系统发育方法表明，在进化历史中，基础代谢率和C´下降，而Tₗ、Tₘ和TNZ增加。我们的结果表明：1）TNZ和C'极限的差异可能有助于蝙蝠避免环境温度对散热的限制，2）体重和热特性的适应性变化可能影响了蝙蝠的地理分布和节能策略。这些发现有助于理解小型恒温动物如何应对热挑战，揭示了塑造物种生态位和不同环境中生物地理模式的生理和进化机制。
