Sainsbury Laboratory Cambridge, University of Cambridge, Cambridge CB2 1LR, UK.|Institute of Computer Science, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany.|Université de Lausanne, Département dEcologie et dEvolution, Quartier Sorge, 1015 Lausanne, Switzerland.|Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany.|Institute of Computer Science, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany.