Data from: Iridophores and not carotenoids account for chromatic variation of carotenoid-based coloration in common lizards (Lacerta vivipara)

Carotenoids typically need reflective background components to shine. Such
components, iridophores, leucophores, and keratin- and collagen-derived
structures, are generally assumed to show no or little environmental
variability. Here, we investigate the origin of environmentally induced
variation in the carotenoid-based ventral coloration of male common
lizards (Lacerta vivipara) by investigating the effects of dietary
carotenoids and corticosterone on both carotenoid- and background-related
reflectance. We observed a general negative chromatic change that was
prevented by β-carotene supplementation. However, chromatic changes did
not result from changes in carotenoid-related reflectance or skin
carotenoid content but from changes in background-related reflectance that
may have been mediated by vitamin A1. An in vitro experiment showed that
the encountered chromatic changes most likely resulted from changes in
iridophore reflectance. Our findings demonstrate that chromatic variation
in carotenoid-based ornaments may not exclusively reflect differences in
integumentary carotenoid content and, hence, in qualities linked to
carotenoid deposition (e.g., foraging ability, immune response, or
antioxidant capacity). Moreover, skin carotenoid content and
carotenoid-related reflectance were related to male color polymorphism,
suggesting that carotenoid-based coloration of male common lizards is a
multicomponent signal, with iridophores reflecting environmental
conditions and carotenoids reflecting genetically based color morphs.