1. Department of Plant Population Biology, Netherlands Institute of Ecology, PO Box 40, 6666 ZG Heteren, The Netherlands
2. Department of Plant‐Animal Interactions, Netherlands Institute of Ecology, PO Box 40, Rijksstraatweg 6, 3631 AC Nieuwersluis, The Netherlands
3. Department of Ecology, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands