[1] Stanford Univ, Dept Biol Sci, Stanford, CA 94305 USA
[2] Univ Ottawa, Dept Biol, Ottawa, ON K1N 6N5, Canada
[3] Univ Minnesota, Dept Ecol Evolut & Behav, St Paul, MN 55108 USA
[4] Univ Bath, Dept Biol & Biochem, Bath BA2 7AY, Avon, England
[5] Univ Oxford, Dept Plant Sci, Oxford OX1 3RB, England
[6] Univ Auckland, Sch Biol Sci, Auckland 1, New Zealand