Hungry females show stronger mating preferences

Female mating decisions that are based on condition-dependent traits, such as male nutritional state, may be associated with a female’s own condition. In the swordtail fish, Xiphophorus birchmanni, females prefer the chemical cues of well-fed males to cues of food-deprived males. Here we show that this preference is significantly stronger in females when they were experimentally food deprived than when they were well fed. Our results suggest that if females have limited access to food resources, and are themselves food deprived, they will attend to cues indicating male nutritional condition more than when environmental conditions allow for greater access to food. Furthermore, not only is the slope of the preference function condition dependent but also, in all trials, the latency to respond to the presented stimuli was shorter in food-deprived females, suggesting that responsiveness to environmental cues is condition dependent as well. Under natural conditions, females of many species likely experience variation in resource availability. Thus, we predict that covariance between the strength of female preferences and resource availability may be widespread and may represent a common source of female preference variation within and between populations.