Briscoe Natalie J, Handasyde Kathrine A, Griffiths Stephen R, Porter Warren P, Krockenberger Andrew, Kearney Michael R
Department of Zoology, University of Melbourne, Melbourne, Victoria, Australia
Department of Zoology, University of Melbourne, Melbourne, Victoria, Australia.
Biol Lett. 2014 Jun;10(6). doi: 10.1098/rsbl.2014.0235.
How climate impacts organisms depends not only on their physiology, but also whether they can buffer themselves against climate variability via their behaviour. One of the way species can withstand hot temperatures is by seeking out cool microclimates, but only if their habitat provides such refugia. Here, we describe a novel thermoregulatory strategy in an arboreal mammal, the koala Phascolarctos cinereus. During hot weather, koalas enhanced conductive heat loss by seeking out and resting against tree trunks that were substantially cooler than ambient air temperature. Using a biophysical model of heat exchange, we show that this behaviour greatly reduces the amount of heat that must be lost via evaporative cooling, potentially increasing koala survival during extreme heat events. While it has long been known that internal temperatures of trees differ from ambient air temperatures, the relevance of this for arboreal and semi-arboreal mammals has not previously been explored. Our results highlight the important role of tree trunks as aboveground 'heat sinks', providing cool local microenvironments not only for koalas, but also for all tree-dwelling species.
气候对生物的影响不仅取决于它们的生理机能，还取决于它们是否能够通过行为来缓冲气候的变化。物种抵御高温的一种方式是寻找凉爽的小气候，但前提是它们的栖息地提供这样的避难所。在这里，我们描述了一种树栖哺乳动物——考拉（Phascolarctos cinereus）的新型体温调节策略。在炎热天气下，考拉通过寻找并靠在比周围空气温度低得多的树干上休息，增强传导散热。利用热交换的生物物理模型，我们表明这种行为大大减少了必须通过蒸发散热的热量，有可能增加考拉在极端高温事件中的存活率。虽然人们早就知道树木的内部温度与周围空气温度不同，但此前尚未探讨过这对树栖和半树栖哺乳动物的相关性。我们的研究结果突出了树干作为地上“散热器”的重要作用，它不仅为考拉，也为所有树栖物种提供凉爽的局部微环境。
