Evolution in invasive plants implications for biological control.pdf

Evolution in invasive plants: implications for biological control Heinz Mu?ller-Scha?rer1, Urs Schaffner1,2 and Thomas Steinger1 1De?partement de Biologie, Unite? Ecologie et Evolution, Universite? de Fribourg, CH-1700 Fribourg, Switzerland 2CABI Bioscience Centre, CH-2800 Dele?mont, Switzerland Evidence is increasing that invasive plants can undergo rapid adaptive evolution during the process of range expansion. Here, we argue that evolutionary change during invasions will also affect plant–antagonist inter- actions and, thus, will have important implications for biological control programmes targeted at invasive plants. We explore how altered selection in the new range might influence the evolution of plant defence (resistance and tolerance) and life history. The degree to which such evolutionary processes might affect bio- logical control efficacy is largely unexplored. We hope that, by testing the hypotheses that we propose here, a closer link can be established between biological control and evolutionary biology, to the benefit of both disciplines. BIOLOGICAL INVASIONS (see Glossary) by flowering plants have become more important as a result of increasing anthropogenic activities that affect species dispersal (through trade and travel) and habitat susceptibility (through changes in disturbance regimes) [1]. Although only a few EXOTIC plant species invade natural commu- nities and develop high population densities, those that do so pose one of the most serious threats to biodiversity [2]. Two contrasting, but mutually non-exclusive hypotheses address the relationship between phenotype and invasion success; the first assumes that invaders are pre-adapted with traits that make them successful invaders, whereas the second postulates successful invasion as the outcome of rapid evolutionary change once the species has become established in the new habitat [3]. Adaptation to local conditions is an important form of evolution in plant populations because plants are ses