Local adaptation and phenotypic plasticity in alpine plants

The Alpine environment is characterized by strong variability causing a mosaic of habitat patches. Two fundamental strategies can be contrasted that allow plants to survive in the heterogeneous Alpine landscape. Plants can either adapt by specializing to locally prevailing conditions, a phenomenon referred to as local adaptation, or they can evolve phenotypic plasticity, the ability to respond to a range of conditions they frequently encounter, thereby maintaining high fitness across environments. In my PhD I have investigated the role of local adaptation and phenotypic plasticity for alpine plant survival using the example of Anthyllis vulneraria. Reciprocal transplantation experiments across two spatial scales show that fitness decreases with increasing distance between population origin and transplantation site, demonstrating local adaptation in Anthyllis vulneraria. I also document large population differentiation in the dates of onset and peak of flowering that exceeds neutral population differentiation at microsatellite loci. Moreover I show a functional relationship between the overlap of female and male phases of individual flowers and the degree of inbreeding in populations of Anthylls vulneraria. Phenotypic plasticity in the measured traits was often only small and could not be shown to be of adaptive value. I conclude that populations of Anthyllis vulneraria are locally adapted to the prevailing environmental conditions, and that phenotypic plasticity in response to drought is unlikely to be of adaptive value in the presently studied traits of Anthyllis vulneraria. Genetic variation in key traits such as the timing of flowering rather than phenotypic plasticity therefore appears to be essential for alpine plant survival under climate change.