Pelage luminance has been found in many mammalian systems to follow patterns predicted by Gloger’s rule where darker colored animals are associated with environments that are warmer and more moist. Sciurids have one of the greatest diversities of color patterns and hues among mammalian families. We have used comparative methods to investigate whether the luminance of dorsal pelage in 137 species across Sciuridae conforms to prediction of Gloger’s rule and other background matching expectations. We found using phylogenetic multiple regression, as well as univariate regression, that Sciurids generally conform to the expectations of Gloger’s rule. Darker species are associated with environments with higher primary productivity, higher temperature, higher humidity, and lower solar radiation. Moreover, in support of the predictions of background matching, darker squirrel species were associated with environments with greater soil carbon content and higher fire frequency. Our macroevolutionary study sheds some light on selective pressures that are driving the evolution of coloration in Sciurids, but more comparative research is needed to fully understand other selective pressures that have led to the wide diversity of color patterns and hues.

中文翻译：

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松鼠（松鼠科）皮毛亮度的演变

已在许多哺乳动物系统中发现毛色亮度遵循 Gloger 规则预测的模式，其中颜色较深的动物与更温暖、更潮湿的环境相关联。Sciurids 是哺乳动物家族中颜色图案和色调最多样化的动物之一。我们使用比较方法研究了 137 种 Sciuridae 的背毛亮度是否符合 Gloger 规则的预测和其他背景匹配预期。我们发现使用系统发育多元回归以及单变量回归，Sciurids 通常符合 Gloger 规则的预期。颜色较深的物种与初级生产力较高、温度较高、湿度较高和太阳辐射较低的环境有关。而且，为支持背景匹配的预测，颜色较深的松鼠物种与土壤碳含量较高和火灾频率较高的环境有关。我们的宏观进化研究揭示了推动 Sciurids 颜色进化的选择压力，但需要更多的比较研究来充分了解导致颜色图案和色调的广泛多样性的其他选择压力。