1. The Rocky Mountain Biological Laboratory 8000 County Road 317 Crested Butte CO 81224 USA
2. Department of Ecology & Evolutionary Biology University of Arizona 1041 East Lowell Street Tucson AZ 85721 USA
3. The Arctic Research Centre Aarhus University C.F. Møllers Allé 8 8000 Aarhus C Denmark
4. Ecology Behavior & Evolution Section University of California San Diego 9500 Gilman Drive La Jolla CA 92093 USA