1. Centre of Excellence in Biological Interactions, Department of Biosciences; University of Helsinki; Helsinki Finland
2. Tvärminne Zoological Station; University of Helsinki; J.A. Palménin tie 260 FI-10900 Hanko Finland
3. Okinawa Institute of Science and Technology; 1919-1 Tancha, Onna-son, Kunigami-gun Okinawa 904-0412 Japan
4. Research School of Biology; Australian National University; Canberra ACT 0200 Australia
5. Centre for Social Evolution; University of Copenhagen; Universitetsparken 15 2100 Copenhagen Denmark