Centro Universitario Amecameca, Universidad Autónoma del Estado de México, Estado de México, Instituto Literario No. 100, Col. Centro, Toluca, CP 50000, México.
Doctorado en Ciencias Agropecuarias y Recursos Naturales, Universidad Autónoma del Estado de México, Instituto Literario No. 100, Col. Centro, Toluca, Estado de México, CP 50000, México.
Int J Biometeorol. 2024 Jul;68(7):1421-1435. doi: 10.1007/s00484-024-02677-7. Epub 2024 Apr 23.
Temperature is one of the most important factors in the life histories of ectotherms, as body temperature has an undeniable effect on growth, activity, and reproduction. Lizards have a wide variety of strategies to acquire and maintain body temperature in an optimal range. The "Thermal Melanism Hypothesis" proposes that individuals with lower skin reflectance can heat up faster as a result of absorbing more solar radiation compared to lighter conspecifics. Therefore, having a darker coloration might be advantageous in cold habitats. Dorsal skin reflectance has been found to change rapidly with body temperature in several lizard species, and it can also vary over longer, seasonal time scales. These variations may be important in thermoregulation, especially in lizards that inhabit areas with a large temperature variation during the year. Here, we study how dorsal reflectance fluctuates with body temperature and varies among seasons. We compared dorsal skin reflectance at three body temperature treatments, and measured thermal rates (i.e., heat and cool rate, thermic lapse, and net heat gain) by elevation (2500-4100 m) and seasons (spring, summer, and autumn) in the mesquite lizard, Sceloporus grammicus. Our results show that lizards were darker at high elevations and during the months with the lowest environmental temperatures. The rate of obtaining and retaining heat also varied during the year and was highest during the reproductive season. Our results indicate that the variation of dorsal skin reflectance and thermal rates follows a complex pattern in lizard populations and is affected by both elevation and season.
温度是变温动物生活史中最重要的因素之一，因为体温对生长、活动和繁殖都有不可否认的影响。蜥蜴有各种各样的策略来获取和维持身体温度在最佳范围内。“热黑化假说”提出，与浅色同种蜥蜴相比，皮肤反射率较低的个体由于吸收更多的太阳辐射，升温更快。因此，在寒冷的栖息地，颜色更深可能是有利的。在一些蜥蜴物种中，背部皮肤反射率会随着体温的快速变化而变化，而且在更长的季节性时间尺度上也会发生变化。这些变化可能在体温调节中很重要，特别是在那些一年中温度变化很大的蜥蜴中。在这里，我们研究了背部反射率如何随体温波动，并在不同季节之间变化。我们比较了三种体温处理下的背部皮肤反射率，并通过海拔（2500-4100 米）和季节（春季、夏季和秋季）测量了热率（即热和冷却率、热弛豫和净热增益）在Mesquite 蜥蜴 Sceloporus grammicus 中的变化。我们的结果表明，蜥蜴在高海拔地区和环境温度最低的月份颜色更深。获得和保持热量的速度也随时间而变化，在繁殖季节最高。我们的结果表明，背部皮肤反射率和热率的变化在蜥蜴种群中呈现出复杂的模式，受海拔和季节的影响。
