[1] Univ Alaska, Inst Arctic Biol, Fairbanks, AK 99775 USA
[2] Stanford Univ, Dept Biol Sci, Stanford, CA 94305 USA
[3] Stanford Univ, Inst Int Studies, Stanford, CA 94305 USA
[4] Univ Calif Berkeley, Dept Integrat Biol, Berkeley, CA 94720 USA
[5] Kalamazoo Coll, Dept Biol, Kalamazoo, MI 49006 USA
[6] Western Washington Univ, Dept Biol, Bellingham, WA 98225 USA
[7] CNRS, UPR 9056, Ctr Ecol Fonct & Evolut, F-34293 Montpellier 05, France
[8] Univ Buenos Aires, Fac Agron, Catedra Ecol, RA-4453 Buenos Aires, DF, Argentina
[9] Univ Buenos Aires, Fac Agron, Inst Fisiol & Ecol Vinculadas Agr, RA-4453 Buenos Aires, DF, Argentina
[10] Univ Minnesota, Dept Ecol Evolut & Behav, St Paul, MN 55108 USA
[11] Univ Nacl Cordoba, Fac Ciencias Exactas Fis & Nat, Inst Multidisciplinario Biol Vegetal, RA-5000 Cordoba, Argentina