Data from: Mechanisms of colour variation in the frillneck lizard: geographic differences in pigment contents of an ornament

Animal colouration has evolved in contexts such as communication, camouflage and thermoregulation. The majority of studies of animal colouration focus on its adaptive benefits, while its underlying mechanisms have received less attention despite their potential influence on adaptive benefits. In fish and reptiles for instance, colour variation from yellow to red can be produced by carotenoid and/or pteridine pigments, which differ dramatically in the way they are obtained (carotenoids through diet and pteridines synthesised de novo). Hence, potential adaptive benefits could differ greatly depending on the relative contribution to colouration of different pigments. Here, we investigate the mechanisms underlying colour variation in the frill of the Australian frillneck lizard (Sauropsida: Chlamydosaurus kingii). Frill colour varies between populations across the species’ range (red, orange, yellow or white). We argue that this geographic variation results from different concentrations of carotenoids and pteridines in the frill. Frill carotenoid concentrations were lower in eastern populations (yellow and white forms), and pteridines were present only in the red and orange forms, thereby explaining their redder hues. The observed geographic variation in frill carotenoids suggests variation in carotenoid availability across the species’ range, which is backed up by the finding that plasma carotenoid concentrations were higher in the red (western) compared to the yellow (eastern) form. Although no correlations were found between individual colour measurements, frill pigments and plasma carotenoids, our results suggest that selective pressures vary across the species’ range and we speculate that predation pressures and/or intra-sexual signalling context differ among forms.