Behavioural plasticity in physically variable microhabitats: a field test of potential adaptive consequences in male collared lizards (Crotaphytus collaris)

Variation in physical attributes of microhabitats is often neglected in studies of animal mating systems. In habitats with abundant refuges, stealthy mating tactics may be effective because non-territorial males can readily hide from territorial males. Anthropogenic physical alterations at our site allowed us to compare social behaviour and reproductive success in male collared lizards occupying two types of rip-rap microhabitat. In complex microhabitat, non-territorial males evaded detection by moving within interstitial spaces beneath large surface rocks. Simplified patches had less cover and were smaller, which crowded males closer to both male rivals and females. Although the basic social structure was similar in the two microhabitats, the defensive and courtship behaviours of males and the relative payoff of territory defence differed. In simplified microhabitat, territory maintenance did not require increased aggression even though male rivals were closer. In simple microhabitats, territorial males defended smaller areas but courted females more frequently and monopolized a larger proportion of their offspring than territorial males in complex microhabitats. Our findings suggest that decreased cover and increased visibility increased the net benefit of territorial mating tactics. This study illustrates the utility of populations altered by humans for tests of evolutionary questions.