Ornament size and colour as alternative strategies for effective communication in gliding lizards

Sexual ornamentation needs to be conspicuous to be effective in attracting potential mates and defending territories and indeed, a multitude of ways exists to achieve this. Two principal mechanisms for increasing conspicuousness are to increase the ornament's colour or brightness contrast against the background and to increase the size of the ornament. We assessed the relationship between the colour and size of the dewlap, a large extendible throat-fan, across a range of species of gliding lizards (Agamidae; genus Draco) from Malaysia and the Philippines. We found a negative relationship across species between colour contrast against the background and dewlap size in males, but not in females, suggesting that males of different species use increasing colour contrast and dewlap size as alternative strategies for effective communication. Male dewlap size also increases with increasing sexual size dimorphism, and dewlap colour and brightness contrast increase with increasing sexual dichrom...

性饰（sexual ornamentation）需具备足够醒目性，方能有效吸引潜在配偶、捍卫领地，而实现这一目标的途径繁多。提升醒目性的两大核心机制，分别为增强性饰与背景间的色彩或亮度对比度，以及扩大性饰自身尺寸。我们针对马来西亚与菲律宾境内的多类滑翔蜥蜴（鬣蜥科Agamidae；飞蜥属Draco）展开研究，评估其喉扇（dewlap）的色彩与尺寸间的关联——该喉扇为大型可伸展的喉部扇膜结构。我们发现，雄性个体的背景色彩对比度与喉扇尺寸在物种间呈负相关关系，而雌性个体则无此关联，这表明不同物种的雄性会将增强色彩对比度与扩大喉扇尺寸作为有效通讯的替代性策略。雄性喉扇尺寸还会随两性体型二态性（sexual size dimorphism）的增强而增大，喉扇色彩与亮度对比度则会随两性色彩二态性（sexual dichromatism）的提升而增强……