1. Division of Biochemistry and Molecular Biology, University of California, Berkeley, California 94720-3202
2. Museum of Vertebrate Zoology, University of California, Berkeley, California 94720-3160
3. Conservation Genetics Laboratory, Department of Biology, San Francisco State University, San Francisco, California 94132-1722
4. Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211
5. Department of Biological Sciences, University of California, Santa Barbara, California 93106