Determinants of sexual differences in escape behavior in lizards of the genus Anolis: a comparative approach

Abstract

Males and females are known to differ in a whole suite of characteristics, such as morphology, physiology, ecology, and behavior. Intersexual differences are generally believed to arise because of differences in selective pressures on either sex. In this study, we investigated whether intersexual differences in escape behavior exist in lizards of the genus Anolis, and whether these could be explained by intersexual differences in body size and/or microhabitat use. To do so, we compared the behavioral response to an approaching human predator in the field in males and females of 12 Anolis species. We found that ecomorphs and sexes differ greatly with respect to escape behavior. Twig anoles have the shortest approach distance (i.e., distance between the observer and the lizard when it starts fleeing) and final distance (i.e., distance between the observer and the lizard when it stops moving), compared with the other ecomorphs. The distance fled, on the contrary, is greatest in twig anoles. Also, females flee less soon and run over shorter distances than do males. Since twig anoles are considered the most cryptic anoles, and females may be less conspicuous than males, these results corroborate the idea that well camouflaged animals allow predators to come closer. The interspecific variation in sexual dimorphism in escape behavior, however, cannot be explained by the interspecific variation in sexual size dimorphism or sexual dimorphism in microhabitat use. Thus, escape behavior appears determined by different factors in males and females.