1. Department of Biology, Virginia Tech, Blacksburg, VA 24061 USA;
2. Present address: Biology Department, Randolf‐Macon Women’s College, Lynchburg, VA 24503, USA
3. Joseph W. Jones Ecological Research Center, Route 2, Box 2324, Newton, GA 31770, USA;
4. Department of Biology, University of North Carolina at Greensboro, Greensboro, NC 27402, USA;