Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland.
Department Evolutionary Genetics, Leibniz Institute for Zoo and Wildlife Research, D-10315 Berlin, Germany.
Biol Open. 2022 Apr 15;11(4). doi: 10.1242/bio.059064. Epub 2022 Apr 4.
Torpor is a state of controlled reduction of metabolic rate (M) in endotherms. Assigning measurements of M to torpor or euthermy can be challenging, especially when the difference between euthermic M and torpid M is small, in species defending a high minimal body temperature in torpor, in thermolabile species, and slightly below the thermoneutral zone (TNZ). Here, we propose a novel method for distinguishing torpor from euthermy. We use the variation in M measured during euthermic rest and torpor at varying ambient temperatures (Ta) to objectively estimate the lower critical temperature (Tlc) of the TNZ and to assign measurements to torpor, euthermic rest or rest within TNZ. In addition, this method allows the prediction of M during euthermic rest and torpor at varying Ta, including resting M within the TNZ. The present method has shown highly satisfactory results using 28 published sets of metabolic data obtained by respirometry on 26 species of mammals. Ultimately, this novel method aims to facilitate analysis of respirometry data in heterothermic endotherms. Finally, the development of the associated R-package (torpor) will enable widespread use of the method amongst biologists.
休眠是恒温动物控制代谢率（M）降低的一种状态。将 M 的测量值分配给休眠或常温状态可能具有挑战性，尤其是当常温状态下的 M 和休眠状态下的 M 之间的差异很小时，在那些在休眠中保持高最小体温的物种中，在热敏性物种中，以及略低于热中性区（TNZ）时。在这里，我们提出了一种区分休眠和常温状态的新方法。我们使用在不同环境温度（Ta）下测量的常温休息和休眠期间 M 的变化来客观估计 TNZ 的下临界温度（Tlc），并将测量值分配给休眠、常温休息或 TNZ 内的休息。此外，该方法允许预测在不同 Ta 下的常温休息和休眠期间的 M，包括在 TNZ 内的休息 M。使用 26 种哺乳动物的呼吸测量法获得的 28 组已发表的代谢数据集，本方法显示出了非常令人满意的结果。最终，这种新方法旨在促进对异温恒温动物呼吸测量数据的分析。最后，相关 R 包（torpor）的开发将使该方法能够在生物学家中广泛使用。
