1. Ecology Program, Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79409-3131;
2. National Center for Ecological Analysis and Synthesis, University of California, Santa Barbara, California 93101-3351
3. Division of Biology, Kansas State University, Manhattan, Kansas 66506-4901;
4. Ecology Program, Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79409-3131
5. National Center for Ecological Analysis and Synthesis, University of California, Santa Barbara, California 93101-3351;