“For major advances to take place…a population with a high degree of genetic variability must be placed in an environment which is rapidly changing… the evolutionary lines most likely to take advantage of a changing environment are those in which recombination is raised to a maximum. This is accomplished most effectively by mass hybridization between populations having different adaptive norms.” (Stebbins, 1959) More than 50 years after Stebbins’ insightful review of hybridization and the origins of plant diversity, ecologists are faced with the stark truth that nearly 25% of the earth’s land surface has been converted to grazed or cultivated crop land. Changing land use, in concert with a changing climate, is likely to alter the impact of agricultural species on marginal populations and communities and increase the probability of crop weed hybridization. Hybridization between crops and weeds will be more likely, and the subsequent evolution of weedy forms is nearly certain to follow. As a result, “weedy" habitats found at the interface of crop lands and native habitats will constitute a major repository of ecological diversity and function. Stebbins suggests that these environments hold the potential for the rapid evolution of new plant forms. As the earth's life support systems are increasingly affected by crops and influenced by weeds, the study of marginal environments becomes more pressing. We propose a symposium examining ecology and evolutionary processes at the interface of domesticated and native species. Within the framework, symposium speakers will address a series of topics to foster discussion among ecologists, evolutionary biologists, geographers and genomicists to understand the evolution in marginal environments.