Intraspecific variation in antipredator responses of three species of lizards (Liolaemus):: Possible effects of human presence

Although humans are commonly used as a surrogate predator to assess the antipredator behavior of lizards, little is known about the effects that life associated with humans may have on the escape behavior of lizards. Here we examine the effects that coexistence with humans may have on the antipredator mechanisms in three species of Liolaemus (Tropiduridae). For each species we compared two populations exposed to different human densities, to test the null hypothesis that there is no interpopulational variation in the response to an approaching human in the field. Also it was determined whether coexistence with humans would affect the behavioral and physiological antipredator responses to a model of a natural predator in the laboratory. Lizard populations that were exposed to a high human density allowed a closer proximity of humans in the field, and decreased their rate of movement and breathing intensity in response to the presentation of a predator model in laboratory experiments. We discuss the effects humans may have upon the lizards antipredator behavior toward humans and natural predators.