Differences in dispersal are more important than differences in demography to the greater invasion speed of invasive plant species than their noninvasive relatives

Background/Question/Methods

By understanding the relative importance of different processes to invasion speed we can better predict and control biological invaders, thus helping to preserve natural resources and ecosystem functioning. We conducted a phylogenetically controlled comparative study of the roles of demography and dispersal in governing invasion speed for five pairs of invasive and noninvasive relatives. We parameterized integrodifference invasion speed models with empirical demographic and dispersal information from a common environment at Tyson Research Center, St. Louis, Missouri, USA. We then used a Life Table Response Experiment to decompose the relative contributions of differences in demography and dispersal to differences in invasion speed for each pair.

Results/Conclusions

Species classified a priori as invasive had faster projected population growth rates and faster predicted invasion speeds than their noninvasive relatives. Though differences in demography were significant, the differences in dispersal contributed more to the greater invasion speed of the invasive species than did differences in demography. These results suggest that to prevent invasions and preserve biodiversity, and thus earth’s life support systems, we should focus on the role of dispersal in governing spatial spread.