Much historic work has focused on establishing geographical and ecological rules that broadly explain patterns in size variation. We examined geographic variation in Spotted Hyena skull size using geometric morphometrics and spatial statistics. We quantified size variation and sexual size dimorphism of the skull, and evaluated the influence of temperature, precipitation, land cover type, and population density on skull size. We found that female spotted hyenas are slightly larger on average than males. Our analysis of regional differences did not indicate geographic variation in sexual size dimorphism. Skull size of Spotted Hyenas varies with geography but does not adhere to Bergmann’s Rule. The smallest individuals of both sexes occur between −5.00° and 10.00° latitude and east of 28.50° longitude, with larger individuals being found elsewhere. Although Spotted Hyena skull size co-varies in some views with such variables as habitat type and climate indicators, skull size in this species most strongly co-varies with population density. The highest population densities are associated with the smallest skull size, possibly reflecting a relationship between high population density and access to resources. These results suggest that geographic variation in Spotted Hyena skull size is better explained by the energetic equivalence rule than Bergmann’s Rule.

中文翻译：

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斑点鬣狗头骨大小随地理位置的变化有利于能量等效规则而不是伯格曼规则

许多历史工作都集中在建立地理和生态规则上，以广泛解释尺寸变化的模式。我们使用几何形态测量学和空间统计学研究了斑点鬣狗头骨大小的地理变化。我们量化了头骨的大小变化和性别大小二态性，并评估了温度、降水、土地覆盖类型和人口密度对头骨大小的影响。我们发现雌性斑鬣狗的平均体型略大于雄性。我们对区域差异的分析并未表明性别大小二态性的地理差异。斑点鬣狗的头骨大小因地理位置而异，但不遵守伯格曼规则。最小的雌雄个体出现在纬度-5.00°至10.00°之间以及经度28.50°以东，较大的个体出现在其他地方。尽管从某些观点来看，斑点鬣狗的头骨大小与栖息地类型和气候指标等变量共同变化，但该物种的头骨大小与种群密度的共同变化最为强烈。最高的人口密度与最小的头骨尺寸相关，这可能反映了高人口密度和资源获取之间的关系。这些结果表明，能量等效规则比伯格曼规则更好地解释了斑点鬣狗头骨大小的地理差异。