How patchy habitats and isolation affect alpine plant life: genetic diversity, gene flow and mating systems
Alpine habitats are characterized by extreme patchiness and strong natural fragmentation. Spatially isolated populations are probably more the rule than the exception in alpine plant life. Because of the heterogeneity of the landscape and together with their persistence, alpine species are organized into local populations of different size and are highly structured in space. Since plants do not move, the only way for such populations to interact is by the exchange of pollen and seeds. However, the importance of inter-population gene flow in the alpine landscape is poorly known and even less how seed and pollen dispersal affects genetic differentiation and selection pressure in alpine plant species.
We will study the consequences of natural patchiness and limited gene flow for population differentiation and the evolution of reproductive systems in a colonizing plant. In this project we will concentrate on Campanula thyrsoides, a short-lived monocarpic plant from calcareous soils with limited dispersal capacities.
We will analyse the spatial distribution of genetic variation in populations of Campanula using a hirerarchical design. By using nuclear DNA and cpDNA we will be able to separate the respective role of gene flow from pollen and seeds for population differentiation. Furthermore, we will use controlled pollinations and field-based estimates of selfing rates to test the idea that long-distance seed dispersal to isolated habitats of a colonizing plant is selecting for self-fertilization. By experimental demography of Campanula thyrsoides we will explore the demographic consequences of isolation and distance in this species.