Data from: Intensity of male-male competition predicts morph diversity in a colour polymorphic lizard

Sexual selection is one of the main processes involved in the emergence and maintenance of heritable colour polymorphisms in a variety of taxa. Here we test whether the intensity of sexual selection, estimated from population sex ratio, predicts morph diversity in Podarcis muralis, a colour polymorphic lizard with discrete white, yellow, orange, white-orange, and yellow-orange male and female phenotypes (i.e. morphs). In a sample of 116 Pyrenean populations and 5421 lizards, sex ratios (m/f) vary from 0.29 to 2.5, with the number of morphs for each sex ranging from 2 to 5. Male-biased sex ratios are associated with increased morph diversity as measured with Shannon's diversity index. The main factor accounting for this relationship is male morph richness (i.e. the number of morphs). In contrast, female morph diversity is not related to sex ratio. These results suggest a relationship between the intensity of male intrasexual competition and male morph diversity. While other selective forces may interact with sexual selection in maintaining the colour polymorphisms in P. muralis, this evidence suggests a complex evolutionary scenario possibly involving frequency-dependent selection of alternative reproductive tactics and/or complex balancing selection.性选择（Sexual selection）是驱动并维持诸多类群中可遗传颜色多态性（heritable colour polymorphisms）的核心过程之一。本研究旨在检验基于种群性比估算的性选择强度，能否预测欧洲壁蜥（Podarcis muralis）的形态多样性——该物种是一种具有离散型颜色多态的蜥蜴，雌雄个体均存在明确的白色、黄色、橙色、白橙色以及黄橙色表型（即形态型（morphs））。本研究采样覆盖116个比利牛斯山种群，总计5421只蜥蜴，种群性比（雄性/雌性）介于0.29至2.5之间，且两性的形态型数量均为2到5种。以香农多样性指数（Shannon's diversity index）衡量的结果显示，雄性偏向的性比与更高的形态多样性显著相关，介导这一关联的核心因素为雄性形态型丰富度（即形态型的数量）。与之相反，雌性形态多样性与性比并无关联。上述结果表明，雄性种内竞争强度与雄性形态多样性之间存在关联。尽管在维持欧洲壁蜥的颜色多态性过程中，其他选择压力可能与性选择相互作用，但本研究证据仍指向一种复杂的进化场景，其可能涉及替代生殖策略的频率依赖选择，以及/或复杂的平衡选择。