How dewlap color reflects its carotenoid and pterin content in male and female brown anoles (Norops sagrei)

Abstract

Sexually selected colors in animals can be created by multiple pigments (e.g., carotenoids, melanins, pterins), but how these pigment classes interact to generate intraspecific color variation has rarely been tested, especially in reptiles. We examined full-spectrum color variation as well as pterin (i.e., drosopterin) and carotenoid (i.e., xanthophyll) pigment concentrations in the yellow and red sexually dichromatic dewlaps of male and female Brown Anoles (Norops sagrei) to understand their color-generating mechanisms and information content. Reflectance curves showed significant sexual differences in dewlap color that could only partially be explained by pigment composition. For example, drosopterin concentration correlated significantly with red chroma in the male's dewlap center. In females, drosopterin concentration correlated significantly with yellow and red chroma along the dewlap edge. In addition, xanthophyll concentration showed a significant inverse correlation with hue in the center of female dewlaps only. There were several other correlations between pigment concentrations and spectral variables, which hinted at ways that pigments produce color in male and female dewlaps, but these were non-significant after statistically correcting for multiple comparisons. These results demonstrate that sexes differ in how pigment classes influence dewlap spectral variation, but also that there may be other aspects of the integument not measured here that also influence dewlap color.