DISSERTATION RESEARCH: Separating Stochastic Events From Adaptive Evolution During A Biological Invasion

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Invasive species are a worldwide problem, but the degree to which evolutionary processes influence invasibility is poorly understood. A fundamental question is how the process of invasion results in genetic changes that impact the fitness of introduced populations. Addressing this question is complicated by the fact that genetic changes can occur both as a consequence of chance events and by adaptation in response to natural selection. Little is known about the relative influence of these two distinct processes on the success of invaders. The proposed research studies a weedy plant native to Europe and introduced to North America about 200 years ago. Molecular tools will be employed to reveal how chance events during colonization shaped genetic diversity, and to identify the source areas in Europe from which invaders are descended. European and North American plants descended from the same ancestral sources will then be grown together in two experimental gardens within North America to analyze how divergence in adaptively important traits has occurred after controlling for underlying ancestry. The impact of invasive species includes a heavy economic burden, with yearly losses for the U.S. in the billions of dollars. Thus the broader impact of this study will be to advance the understanding of how species become successful invaders, and help illuminate the basis of an important applied problem.