Experimental Test of Predation and Competition Pressures on the Green Anole (Anolis carolinensis) in Varying Structural Habitats

Abstract

The Green Anole, Anolis carolinensis, has been widely studied in terms of its behavioral ecology. However, few studies have simultaneously compared the relative strengths of predation and male competition across temporal and spatial scales in Green Anoles, or other reptile species. We took an indirect experimental approach to compare these forces in Green Anoles by using attacks on clay models as a proxy for the relative intensity of predation and male competition. We measured the proportion of attacks on clay models in two divergent Green Anole populations with distinct habitats (discrete and continuous vegetation) across three seasons (fall, winter, and spring) and found strong evidence for spatial and temporal variation in the relative intensity of each component of selection. The frequency of bites from male Green Anoles was generally higher at an urban locality, whereas the frequency of bites from nonlizards was higher at a natural swamp locality. We also detected temporal variation in the intensity of these processes at both locations, with the intensity of male competition and predation changing in a concomitant fashion, the most intense periods occurring during the fall and spring months and the least intense during the winter months. Our results imply that mortality within some seasonal reptile species is composed of periods of relative calm punctuated by brief but intense “one-two punch” periods of selection.