Effects of two courtship display components on female reproductive behaviour and physiology in the sagebrush lizard

Abstract

Exposure to aggressive or courtship displays of conspecifics has been shown to alter the physiology and behaviour of observers. However, these effects are dependent on the information content of signals. Separate courtship signals that convey redundant information may be expected to have similar effects on female reproductive physiology or behaviour, while those that contain nonredundant information are expected to have differing effects. Using a mechanized model lizard painted to resemble a male sagebrush lizard, Sceloporus graciosus, we presented female sagebrush lizards with either a stationary model or one of two male display types: push-ups, a signal used in both aggressive and courtship displays, and shudders, a display used exclusively during courtship. Females exposed to push-ups showed more rejection behaviour when later paired with a live male lizard and produced less femoral pore secretions on the first day of stimulus presentation than females exposed to shudders. However, females exposed to either display were found in closer proximity to the live male than females exposed to the stationary model. These results suggest that both components of the courtship display (push-ups and shudders) cause lasting but distinctive changes in female behaviour, supporting a ‘multiple messages’ scenario for the evolution of the two signals.