1. Department of Life Sciences; Natural History Museum; Cromwell Road London SW7 5BD UK
2. Environmental Change Research Centre; Department of Geography; University College London; Gower Street London WC1E 6BT UK
3. Grupo de Palinología y Paleoecología Tropical; Departamento de Ciencias Biológicas; Universidad de Los Andes; Cra 1A No. 18A-12 Bogotá Colombia
4. Lake Group and Arctic Research Centre; Department of Bioscience; Aarhus University; Ny Munkegade 116, DK-8000 Aarhus C Silkeborg Denmark