Laboratorio de Ecología, Biología Evolutiva y Comportamiento de Herpetozoos (LEBECH), Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA), CONICET-UNCOMA, Quintral 1250, Bariloche, 8400, Río Negro, Argentina.
Universidad Nacional del Comahue, Quintral 1250, Bariloche, 8400, Río Negro, Argentina.
Zoology (Jena). 2020 Aug;141:125774. doi: 10.1016/j.zool.2020.125774. Epub 2020 Apr 27.
Body temperature affects various aspects of ectotherm biology. Reptiles, as ectotherms, gain and control their temperature mainly through behavioural adjustments, although some body traits may also be advantageous. According to the thermal melanism hypothesis (TMH) dark colour may be thermally advantageous in cold environments. Additionally, differences in thermoregulatory capacity may also affect performance. We analysed the role of melanism in the thermoregulation and sprint speed performance of three species of Liolaemus lizards from Argentinean Patagonia. Liolaemus shitan, L. elongatus and L. gununakuna are phylogenetically close, with similar body sizes and life history traits, but differ in their melanic colouration, L. shitan being the darkest and L. gununakuna the lightest species. We estimated sprint speed performance curves and heating rates, and recorded final body temperature and sprint speed achieved after a fixed heating time, from two different initial body temperatures, and with and without movement restriction. Performance curves were similar for all the species, but for L. gununakuna the curve was more flattened. Darker species showed faster heating rates, ran faster after fixed heating trials at the lowest temperature, and reached higher body temperatures than L. gununakuna, but this was compensated for by behavioural adjustments of the lighter lizards. Similarity of sprint speed performance may be due to the conservative nature of this character in these species, while variation in heating ability, particularly when starting from low temperatures, may reflect plasticity in this trait. The latter provides support for the TMH in these lizards, as melanism helps them increase their body temperature. This may be especially advantageous at the beginning of the day or on cloudy days, when temperatures are lower.
体温会影响变温动物生物学的各个方面。作为变温动物的爬行动物主要通过行为调整来获得和控制体温，尽管某些身体特征也可能具有优势。根据热黑化假说（TMH），深色在寒冷环境中可能具有热优势。此外，体温调节能力的差异也可能会影响表现。我们分析了黑化在三种来自阿根廷巴塔哥尼亚的 Liolaemus 蜥蜴的体温调节和冲刺速度表现中的作用。Liolaemus shitan、L. elongatus 和 L. gununakuna 是亲缘关系密切的物种，具有相似的体型和生活史特征，但在黑化程度上存在差异，L. shitan 是最暗的物种，L. gununakuna 是最浅的物种。我们估计了冲刺速度表现曲线和加热率，并记录了在固定加热时间后从两个不同初始体温达到的最终体温和冲刺速度，同时考虑了有无运动限制。所有物种的表现曲线相似，但 L. gununakuna 的曲线更为平坦。较暗的物种表现出更快的加热率，在最低温度下进行固定加热试验后跑得更快，并且达到的体温高于 L. gununakuna，但这被较浅蜥蜴的行为调整所补偿。冲刺速度表现的相似性可能是由于这些物种中该特征的保守性质，而加热能力的变化，特别是在从低温开始时，可能反映了该特征的可塑性。后者为这些蜥蜴中的 TMH 提供了支持，因为黑化有助于它们提高体温。这在一天开始或阴天、温度较低时可能特别有利。
