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 for...性选择（sexual selection）是促成并维持多类群可遗传体色多态性的核心演化过程之一。本研究旨在验证：基于种群性比（population sex ratio）估算的性选择强度，能否预测壁蜥（Podarcis muralis）的形态多样性——该物种为具有体色多态性的蜥蜴，雌雄个体均存在明确区分的白色、黄色、橙色、白橙色及黄橙色表型（即形态型，morphs）。本研究纳入116个比利牛斯山种群的采样样本，共计5421只蜥蜴，其种群性比（雄/雌）波动范围为0.29至2.5，且各性别的形态型数量介于2至5种。以香农多样性指数（Shannon's diversity index）衡量时，雄性偏倚的性比与更高的形态多样性呈显著正相关。该关联的核心驱动因素为雄性形态型丰富度（即形态型的数量）。与之相反，雌性形态多样性与种群性比无显著关联。上述结果表明，雄性种内竞争（male intrasexual competition）强度与雄性形态多样性之间存在关联。尽管其他选择……