Ecological speciation and postglacial polymorphism

The mechanisms are often associated to trophic adaptations in behaviour and morphology which occur frequently along resource gradients in the pelagic-benthic axis. We combine field studies (ecology and lifehistory-traits) with molecular tools and experimental studies. The reasons of the origin of resource polymorphism range from allopatric divergence under geographical isolation during the last Ice Age, to divergent natural selection in sympatry. Species pairs of European whitefish Coregonus lavaretus and Arctic charr Salvelinus alpinus are excellent model species as they have large plasticity in phenotypic and life-history traits and strong niche diversifications. Postglacial lakes are unique hotspots for studying early evolution processes as they are: i) young in evolutionary time (<12,000 years), ii) replicated, discrete, but variable entities in the landscape, iii) pristine systems with vacant niches and low species packing, iv) inhabitant of sympatric fish morphs.