1. Department of Forest Ecology and Genetics, INIA-CIFOR, Ctra. de la Coruna km 7.5, Madrid, Spain
2. Department of Biology, University of Minnesota-Duluth, 1049 University Drive, Duluth, MN, USA
3. Department of Ecology, Evolution and Behavior, University of Minnesota, 1479 Gortner Avenue, Saint Paul, MN, USA