An experimental test of the ideal despotic distribution

Abstract

1. Ideal despotic distribution theory predicts that the quality of habitat controlled by territorial animals should vary depending on their competitive ability and the availability of resources. 2. In environments where resources have a patchy distribution, males that monopolize high quality territories may require less territory area than males in low quality areas. This has been a difficult premise to test in the wild owing to logistical constraints regarding manipulation of relevant resources and accurate measures of territory distributions. 3. We present results from an experimental test of ideal despotic distribution theory in a wild population of side-blotched lizards, Uta stansburiana (Baird and Girard). 4. We manipulated thermal resources on territories by shuttling rocks between dyads of neighbouring male territories. Manipulations created high quality territories by significantly increasing the variance in temperatures available for thermoregulation. 5. Experimentally improved quality territories (rock addition) became smaller after treatment, while reduced quality territories (rock removal) became larger. 6. Males on improved and reduced quality territories had equal numbers of females, resulting in higher densities of females on the smaller high quality territories. 7. Densities of the snake Masticophis flagellum, the dominant predator of Uta stansburiana, were higher on reduced quality territories. 8. Progeny released to experimental plots had significantly higher growth-rates and survival on experimentally improved sites relative to their neighbours on low quality territories. 9. Our results demonstrate both the ecological factors that drive the ideal despotic distribution, and the fitness consequences of high and low quality territories to lizards.