1. Whittier College, Department of Biology, Whittier, California 90608, U.S.A. (e-mail: ),
2. Pennsylvania State University, Department of Biology, Shenango Campus, Sharon, Pennsylvania 16146, U.S.A. (e-mail: ),
3. University of Oklahoma, Sam Noble Oklahoma Museum of Natural History, Norman, Oklahoma 73072, U.S.A. (e-mail: ), and
4. University of Kansas, Department of Ecology and Evolutionary Biology, Lawrence, Kansas 66045, U.S.A. (e-mail: )