Abstract
Rosa rugosa from NE Asia is an invasive exotic species in N Europe and NE North America. It constitutes a major concern for nature conservation along the coasts of the North Sea and the Baltic. Why did Rosa rugosa become invasive? Two kinds of causes may be distinguished, evolution and ecology. A genetic change may have taken place in the exotic range since the introduction and may have been caused by altered selective pressure in the new environment or by introgression from native or cultivated relatives not occurring in the native range. Alternatively, R. rugosa may have escaped from its natural enemies (insects and fungi), which limit population growth and plant vigour in its native range. Circumstantial evidence points to both evolutionary and ecological factors, but rigorous testing is needed. We need to know the relative merits of these factors, in the case of R. rugosa and in general, should we be able to prevent further spread of this particular species, and the introduction of new invasive species. The project will test for quantittive genetic differences between Asian and exotic strains in common garden experiments, and will test the enemy release hypothesis by reducing general herbivory and disease under field conditions with competitive neighbours. Experiments will be carried out in parallel in the native and exotic ranges. In addition, the population dynamics will be studied in order to identify the life cycle stage most sensitive to control measures.
Sweden