Climate change and weed adaptation: can evolution of invasive plants lead to greater range expansion than forecasted?

P>Invasive plants are frequently viewed as harbingers of climate change owing to their potential to cause economic and ecological damage in the process of expanding their ranges. Models are being developed to help predict the range expansion of these plants, based on known tolerance ranges. Success of weeds has often been attributed to an 'all-purpose genotype', implying a high level of phenotypic plasticity. However, recent work has shown that many species are capable of relatively rapid genetic change as well, enhancing their ability to invade new areas in response to anthropogenic ecosystem modification. We thus predict that range expansion by many invasive species will exceed that predicted by modelling approaches that do not consider potential evolutionary change. We highlight a number of cases where weeds have expanded their latitudinal ranges or are predicted to do so in response to climatic selection pressures. We also list ten traits as likely targets for natural selection under climate change. The lag phase commonly observed for invasive species may frequently be a result of the time needed for the invader to evolve to fit the new habitat. During this present period of climate change, many invasive plant populations are likely to be in the process of developing adaptations that could lead to exponential population growth in the near future. Thus, assessment of the risk of invasive species owing to changing climate must incorporate evolutionary potential.