Data from: Discrimination of signal carotenoid content using multidimensional chromatic information

Red, orange and yellow carotenoid-based ornaments, which are widely used as sexual signals in many birds, fish and reptiles, are known to exhibit multidimensional chromatic variation as a result of both the concentration and relative proportions of different constituent carotenoids with differing spectral properties. This is thought to reflect intrinsic variation in signaller quality, making it a useful basis for female choice. However, whether females are able to discriminate relevant variation in carotenoid concentration and/or composition independently of each other, and of other phenotypic or behaviour traits, and if so, how this mediates their choice, is poorly understood. Here, female three-spined sticklebacks (Gasterosteus aculeatus) were presented with computer-animated courting males that varied exclusively in the appearance of their carotenoid-based colouration; specifically, each male’s signal provided a perceptual match for carotenoid colouration expressed by live males with known underlying carotenoid content, thereby providing a biologically-relevant signal while precluding confounding traits influencing female choice. Females were able to discriminate between prospective mates solely on the basis of perceived variation in the allocation of carotenoids to males’ sexual signals, and exhibited a strong preference for males with colouration indicative of higher concentrations of carotenoids in their signal, rather than in response to perceived variation in the relative proportion of constituent carotenoids. This has important implications for our understanding male signalling strategies and the information content of carotenoid-based sexual signals.

在诸多鸟类、鱼类与爬行类中被广泛用作性信号的红、橙、黄三类基于类胡萝卜素的体色饰纹（carotenoid-based ornaments），已知会因不同组成类胡萝卜素的浓度及其相对占比而呈现多维度色彩变异——这些类胡萝卜素各自具备独特的光谱特性。这类色彩变异被认为能够反映信号发送者的内在品质差异，因此成为雌性择偶决策的可靠参考依据。然而，目前学界尚未明确：雌性能否在不受其他表型或行为性状干扰的前提下，独立区分类胡萝卜素浓度与组成比例的相关变异；若可以，它们又如何通过该变异调控择偶行为。本研究以雌性三棘刺鱼（Gasterosteus aculeatus）为实验对象，向其展示经计算机动画制作的求偶雄性个体——这些动画雄性仅在基于类胡萝卜素的体色外观上存在差异。具体而言，每只动画雄性的信号均与实际雄性所表达的类胡萝卜素体色感知匹配，且其类胡萝卜素基础含量已知，由此在构建具有生物学相关性的信号的同时，排除了其他会干扰雌性择偶的混淆性状。实验结果表明，雌性仅能通过感知雄性性信号中类胡萝卜素分配的变异来区分潜在配偶，且对体色信号中类胡萝卜素浓度更高的雄性表现出强烈的择偶偏好，而非对组成类胡萝卜素的相对占比变异产生响应。该研究结果对于我们理解雄性的信号策略以及基于类胡萝卜素的性信号所承载的信息内涵，具有重要的启示意义。