Abstract

Animals in high predation environments tend to react to predators more quickly and effectively compared to animals in low predation environments. Because antipredator behavior can be increased by predator introductions and decreased by predator losses, we examined whether populations occurring outside of a predator's range are associated with behavioral changes. Genetic evidence indicates that Side-blotched Lizards (Uta stansburiana) radiated into the northern portions of their range relatively recently and rapidly. As such, Uta populations exist in the presence or absence of various predators. We studied four populations of Uta in Oregon and Nevada to test for behavioral differences among populations that co-occur with different predators. We measured several behavioral traits thought to be associated with predator exposure and used predation-pressure estimates for each population to show that movement and display behavior vary among sites but tend to be negatively affected by predation environment. However, an important determinant of these relationships is the estimate of predation pressure itself. These results suggest that conspicuous behavior in lizards is reduced in the face of increased predation pressure but that variation among populations may obscure this pattern.