Rapid beard darkening predicts contest outcome, not copulation success, in bearded dragon lizards

Abstract

Rapid colour change is widespread in animals and allows them to respond dynamically to the physical and social environment. However, few studies have examined the information conveyed by dynamic colour signals in different social contexts, such as courtship and rivalry contests. Furthermore, dynamic colour change on different body regions may be subject to different selection pressures and therefore serve different functions. We tested whether male colour or colour change predicts contest outcome in male–male interactions or the likelihood of copulation attempts in male–female interactions in the central bearded dragon, Pogona vitticeps . The extent of beard darkening strongly predicted contest outcome, but neither colour (beard, dorsal) nor colour change predicted copulation attempts. Dorsal colour showed little consistent change and did not predict contest outcome or copulation attempts. Previous work shows that dorsal but not beard colour change occurs in response to both background colour and temperature in the laboratory and in the wild. Taken together, these results indicate that dynamic colour change in bearded dragons varies in relation to social context and can serve different functions depending on the body region. Our results add to the growing appreciation of how rapid colour change enables animals to accommodate the multiple functions of colour, including communication to different receivers, camouflage and thermoregulation. • Male bearded dragon lizards change colour during interactions with other lizards. • Winners had darker beards, and their beard changed more than those of losers. • Residency was the strongest predictor of contest outcome. • Neither colour nor the extent of colour change predicted copulation attempts.