Animal color signals evolve in response to selection by visual systems that perceive them, ambient light spectra that illuminate them, and features of the background against which they are juxtaposed. In Anolis lizards, males use a colorful dewlap, together with head-bobbing displays, to deter conspecific rivals and to attract females. As most anoles are both arboreal and sympatric with one or more congeners, selection should favor dewlap colors that contrast sufficiently with the visual background of foliage to be detectable, and that differ reliably from dewlaps of sympatric congeners to be discriminable. We used spectroradiometry and computational visual modeling for five species of closely related Jamaican anoles to calculate the detection probability of each species' dewlap in each of the species' light habitats. Despite substantial interspecific differences in dewlap colors, as well as moderate differences in habitat light spectra, results of our analyses did not support the prediction that a given species' dewlap should be more detectable in its “own” light habitat than in those of sympatric congeners. Rather, dewlaps tended to perform similarly across most light environments. Our results resemble those reported for Puerto Rican anoles, and we discuss potential reasons why Anolis dewlap color design does not appear to be optimized for specific light habitats.

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