Abstract
Colors are important vehicles for social signals in many taxa. In Squamata, previous studies have linked color characteristics and chromatic diversity to sexual selection and, particularly, species showing male-biased body size dimorphism also showed male-biased dichromatism and color diversity. Sexual dichromatism may occur in body regions used for conspecific communication and it may be expressed at wavelengths, such as ultraviolet, easily perceivable by conspecifics. We tested this prediction in a social lizard model, Tropidurus spinulosus, using spectrophotometry and visual modelling which enable colors to be interpreted as the individuals of the same taxon see them. Our results indicate that sexual dichromatism occurs in the ventral regions and the flanks, which are the body regions involved in sexual displays. Males show greater color diversity, having larger color volumes and more contrasting colors. These findings reinforce the idea that sexual selection towards males is coupled with the evolution of male-biased, diverse, coloration which could act as a signal in social reproductive contexts.
Highlights
Colors often act as social signals in many taxa[1]
This work contributes to the understanding of dichromatism in T. spinulosus by elucidating associations between color characteristics and body regions in both sexes, suggesting that sexual selective pressures are operating through chromatic communication
Our results show that T. spinulosus is perceived by conspecifics as sexually www.nature.com/scientificreports
Summary
Color signals evolved to be clearly distinguishable by the visual system of intended receivers and provide information that can be used to take behavioural decisions[2,3] In lizards they may be used in the recognition of conspecifics, mate choice and intra-sexual interactions[4,5]. Color patterns are subject to both ecological and sexual pressures[6,7], which may act differentially on sexes, leading to different colorations (hereafter, sexual dichromatism)[8] In some taxa, such as Lacertidae and Agamidae the degree of dichromatism is positively associated with sexual size dimorphism[7,9,10], a classical proxy of the intensity of sexual selection in lizards since in many species it has been related to both intrasexual (male-male interactions) and intersexual (mate choice) dynamics[11,12]. Elucidating associations between color characteristics and body regions involved in chromatic communication may contribute to reveal the selective pressures acting on dichromatism
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