1. Evolutionary Ecology Group, Department of Biology University of Antwerp Wilrijk B‐2610 Belgium
2. Interuniversity Institute for Biostatistics and statistical Bioinformatics Hasselt University Diepenbeek B‐3590 Belgium
3. Department of Ecology and Evolutionary Biology Princeton University Princeton New Jersey 08544
4. Eco‐Epidemiology Group, Department of Biomedical Sciences Institute of Tropical Medicine Antwerp B‐2000 Belgium