Male preference for sexual signalling over crypsis is associated with alternative mating tactics

Abstract

Changing body colour in animals generally reflects a conflict between two selection pressures, camouflage and social signalling. Chameleons are among the few organisms that resolve this conflict by rapid and temporary change in body colour for both background matching and social display. Male common chameleons, Chamaeleo chamaeleon, employ two alternative mating tactics, dominants and subordinates, both of which are associated with long-term body colour patterns and instantaneous colour displays during social encounters. Hence, males present a good model in which to study the influence of mating tactic on the decision of whether to remain cryptic or to signal. We exposed individuals to two conflicting external stimuli: background manipulations, which challenge camouflage, and the presence of a female, which stimulates sexual signalling. No individuals of either mating tactic responded to background manipulation except when the shift was from green to brown background or vice versa. Ambient temperatures affected colour matching but not sexual signalling, while body temperature affected neither. Males ignored the background colour and prioritized being distinctive when encountering females. As such, males were more likely to engage in sexual signalling than crypsis. Subordinate sneakers signalled females more frequently than the dominant, female-guarding males, suggesting that sneakers rapidly signal females their intentions when the dominant is out of range. Conversely, dominant males may gain little by frequent signalling to the females they guard, while possibly gaining more by diverting this energy towards mate guarding. Our results suggest that specific male mating tactics strongly influence the decision to use crypsis or sexual signalling.