1. Department of Biological Sciences, Program in Ecology and Environmental Science, 5722 Deering Hall, Room 202, University of Maine, Orono, Maine 04469, U.S.A.
2. Laboratory of Genomic Diversity, FCRDC/NCI, Building 560, Room 1184, Frederick, Maryland 21702‐1201, U.S.A.
3. United States Department of Agriculture, Amityville, New York 11701, U.S.A.
4. Department of Animal Ecology, Iowa State University, Ames, Iowa 50011, U.S.A.