Aggressive experience alters place preference in green anole lizards, Anolis carolinensis

Abstract

Males of many species establish territories from which they exclude conspecifics, and experience can influence the defence and stability of territorial boundaries. We used a conditioned place preference (CPP) procedure to determine whether engaging in a form of behaviour associated with territorial defence, aggressive behaviour, was rewarding for male green anoles and whether aggressive experience could alter the spatial/contextual preferences of these territorial lizards. When approached by a male conspecific, or when exposed to their reflection in a mirror, many male anoles show species-typical aggressive behaviours. We repeatedly exposed male anoles to a mirror or the nonreflective back of the mirror in opposing sides of a CPP apparatus that consisted of two contextually distinct chambers connected by a central tunnel. Control animals (N ¼ 10) were exposed to the back of the mirror in both sides of the apparatus. Following conditioning, animals that showed aggressive behaviour (N ¼ 13) when exposed to the mirror during conditioning increased the time that they spent in the side of the apparatus paired with the mirror relative to baseline. In contrast, the preferences of nonaggressive (N ¼ 8) and control animals were unchanged. These findings suggest that engaging in aggressive behaviour (and not simply seeing a conspecific) is rewarding for male green anoles and that aggression-related reward and associative learning could influence the formation and/or maintenance of stable territories.