A hallmark trait of the lizard genus Anolis is the presence of remarkable interspecific variation in dewlap color patterns. Yet, considerable intraspecific variation also occurs in many Anolis species. In Florida different populations of the Green Anole (Anolis carolinensis) exhibit red, pink, magenta, and even greenish-gray dewlaps. To date, comparisons of color variation in this species have used subjective techniques based on human color perception. Instead, we used an objective method—reflectance spectrometry—to quantify A. carolinensis dewlap and body color variation along a transect from northeastern to southwestern Florida. Reflectance readings of local vegetation allowed us to calculate contrast of the lizards with their visual backgrounds. By incorporating local ambient light and A. carolinensis spectral sensitivity into additional calculations, we were able to estimate lizard-background contrast from the perspective of the lizards. Results revealed dewlap and dorsum spectra to differ significantly among most of our study populations, as well as between the lizards and background vegetation. Although increased resemblance of a color signal to the illuminating spectrum will increase the signal's broadcast effectiveness, dewlap colors in our study populations did not resemble the ambient light spectra in their habitats. We consider the potential effects of this species' peculiar spectral sensitivity on the evolution of its dewlap coloration and propose that this coloration may represent a selective compromise to the unusually broad range of light habitats in which A. carolinensis is found. Last, the “gray throated” population of southwest Florida proved to be extraordinary, and we devote special attention to discussing aspects of coloration and contrast in this enigmatic population.
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1 September 2003
Color Variation, Habitat Light, and Background Contrast in Anolis carolinensis along a Geographical Transect in Florida
Joseph M. Macedonia,
Arthur C. Echternacht,
Justin W. Walguarnery
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