The Oxidative Costs of a Colourful Life

Scientists have always been fascinated by the extravagant body colourations of animals. Both females and males produce colourations or even achromatic signals that are used in the context of mate choice, but also in social interactions. Young can also produce colourations that advertise their quality to parents or siblings. Moreover, many species rely on body colourations as warning signals (e.g. Batesian and Müllerian mimicry). The expression of these signals is costly, but the underlying physiological mechanisms are not well understood. In this chapter, I have reviewed the evidence about the role of oxidative stress as a possible mediator of the expression of many of these signals, particularly carotenoid- and melanin-based colourations, or the conspicuous body colourations that are used by some species to signal their unprofitability to predators or to warn and ward off potential competitors.