STEFFEN, J.E.*; SIEFFERMAN, L.; Auburn University: Spectral Properties of the dewlaps of Florida Brown Anoles, Norops sagrei

Male and female Brown Anoles (Norops sagrei) possess a throat fan, or dewlap, that is purportedly used for communication between conspecifics in courtship and territorial interactions. To humans this dewlap appears red-yellow-orange on the lateral portion and yellow on the leading-edge portion of the dewlap. This coloration is though to result from the deposition of pterin (red-orange) and carotenoid (yellow) pigments. Because squamates can perceive coloration in both the ultraviolet (UV) and the human-visible range, we used UV-vis spectrometry to objectively measure coloration from both the lateral and midline region of dewlaps of male and female Norops sagrei. The lateral (red-orange) portion of the dewlap reflected light predominantly in the human visible wavelengths (400-700 nm), whereas the dewlap leading-edge (yellow line) was comprised of spectral peaks in both UV and visible wavelengths (300-700 nm). Principal Components Analysis of the spectra data indicate that brightness (PC1) and chroma (PC2) contribute the greatest amount of variance in spectral measurements for both the lateral (red-orange) and the leading edge (yellow) portions of the dewlap. We found significant sexual dichromatism from both the leading-edge and lateral portions of dewlaps. For both portions of the dewlap, males were darker (PC1) and more chromatic (PC2) than females, suggesting greater pigment deposition in males than females. These differences are discussed in light of chromatophore deposition and sexual selection.