Sexual dimorphism in lizards is determined by ecological and environmental factors. Broadly distributed species may show variation in patterns of sexual dimorphism toward either sex, as well as exhibiting variation in morphological dimensions. In the present study, sexual dimorphism in size and shape attributes was evaluated in three populations of the lizard Sceloporus variabilis from different environments in Mexico. We evaluated the size attributes of 10 morphological variables: snout-vent length (SVL), tibia length (TL), femur length (FeL), forearm length (FoL), interaxial distance (ID), head length (HL), head width (HW), head height (HH), jaw length (JL), and jaw width (JW). We also evaluated the attributes of shape (relative dimensions of the 10 morphological variables). In the size attribute, sexual dimorphism was found, with males being larger than females. In the case of shape, sexual dimorphism was found, with the females being larger in relative dimensions of ID and JW. Also, the males showed larger relative dimensions in TL, FeL and FoL. Differences were found between populations in the dimension of the variables analyzed in each sex. The pattern in size can be explained by sexual selection, where the males of each population maintain larger dimensions to compete for territory and access to females. In shape, females can be favored if they have larger relative ID and JW, as it promotes maintenance of clutch sizes, and use of microhabitats and different consumption of prey types than males. In the case of males, relative dimensions of TL, FeL and FoL may be functioning as important traits for escape from predators. The present study shows the importance of incorporating size and shape variables into analyses of sexual dimorphism among populations of a single species with a wide distribution. These types of studies help to identify the causes that promote sexual dimorphism, as well as the degree of difference among populations that inhabit different environments.

中文翻译：

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蜥蜴 Sceloporus variabilis (Squamata: Phrynosomatidae) 种群大小和形状的性别二态性

蜥蜴的性别二态性是由生态和环境因素决定的。广泛分布的物种可能表现出对任一性别的性二态性模式的变化，以及表现出形态维度的变化。在本研究中，对来自墨西哥不同环境的三个蜥蜴 Sceloporus variabilis 种群的大小和形状属性的性别二态性进行了评估。我们评估了 10 个形态变量的大小属性：鼻腔长度 (SVL)、胫骨长度 (TL)、股骨长度 (FeL)、前臂长度 (FoL)、轴间距离 (ID)、头部长度 (HL)、头部宽度(HW)、头部高度 (HH)、下颌长度 (JL) 和下颌宽度 (JW)。我们还评估了形状的属性（10 个形态变量的相对维度）。在size属性中，发现了性别二态性，男性比女性大。在形状的情况下，发现了性别二态性，雌性在 ID 和 JW 的相对维度上更大。此外，雄性在 TL、FeL 和 FoL 中显示出更大的相对尺寸。在每个性别分析的变量维度上，在人群之间发现了差异。大小的模式可以通过性选择来解释，其中每个种群的雄性保持更大的尺寸来竞争领土和接近雌性。在形状上，如果雌性具有较大的相对 ID 和 JW，则它们会受到青睐，因为它促进了离合器大小的维持、微栖息地的使用以及与雄性不同的猎物类型的消耗。在雄性的情况下，TL、FeL 和 FoL 的相对尺寸可能是逃避捕食者的重要特征。本研究表明将大小和形状变量纳入具有广泛分布的单一物种种群之间的性别二态性分析的重要性。这些类型的研究有助于确定促进性别二态性的原因，以及居住在不同环境的人群之间的差异程度。