Genetic diversity and early colonization success: Testing hypotheses with a model system

Invasive plant species threaten the health of ecosystems worldwide by altering the associations among native species and competing with native plants for limiting resources. Understanding the factors that influence the ability of a plant species to colonize, survive, and reproduce in a novel environment is critical for predicting and controlling invasions. Genetic diversity within a colonizing population may facilitate invasion by allowing the population to maximize resource use, increasing survival and reproductive output. Population-level genetic diversity may also buffer a colonizing population against environmental variability. In this study, we test the importance of population-level genetic diversity for colonization success (as measured by survival and reproduction) using a model plant species, Arabidopsis thaliana. Treatments containing 1, 2, 4, or 8 different genotypes (chosen from a pool of 23) were crossed with high and low density treatments to assess how genetic diversity influences growth and reproduction in more and less stressful (high vs. low density) environments. Preliminary results suggest that increased population-level genetic diversity increases colonization ability via elevated ground cover and, potentially, elevated population-level seed output. A second, ongoing experiment examines whether the level of environmental variability (low – greenhouse vs. high – outdoor) influences the relationship between genetic diversity and colonization success. These studies indicate that predictive power in invasion biology may be increased by considering the genetic diversity of founder populations.