ACKNOWLEDGMENTS My thanks go to Tom Patch whose enthusiasm about and introduction to the life sciences got me started. I am especially grateful to Dr. Martin Trinkle who introduced me to the exciting field of evolutionary biology and whose endless ideas and encouragement led to this and most other studies un which I have been involved. I would like to thank Laurie Mason for hours of discussion about reptilian biology and my introduction to field biology in Kansas. My field research in the Chiracahua Mountains would have lacked some of its joy without the presence and assistance of Sandy and Michael Malcom. Dr. Ray Callinger allowed me access to unpublished data, his study areas, and to his cabin at the Cave Creek Motel. The many evenings discussing biology and the happy days in the field will long be remembered. Special thanks go to my parents, brothers, and sister who helped me along the way. I am sure they suspected it was endless. Also, special thanks to the Alexander Box family for their assistance and friendship. The Department of Zoology, the Graduate School and the National Science Foundation provided financial support for my research and studies. Finally, I would like to thank my committee for their guidance, equipment, financial support, and assistance throughout my studies.