9520752 Atmospheric carbon dioxide is expected to double within the next 80 years due to burning of fossil fuels and deforestation of tropical rainforests. Analyses of ancient air trapped within ice have shown that atmospheric carbon dioxide may have been as low as 50% of the current level approximately 20,000 years ago. We know that many plants increase growth and reproduction when grown under high carbon dioxide and decrease growth and reproduction when grown under low carbon dioxide. We know very little, however, about the evolutionary responses of plants to changing levels of carbon dioxide. That information is needed to: a) accurately predict plant responses under future scenarios of high carbon dioxide, b) understand how plants survived during low carbon dioxide levels of the past and c) determine the processes by which plants evolve in response to changing levels of carbon dioxide. This research will use the annual plant Arabidopsis thaliana as a model system to study the evolutionary responses of plants under low and high carbon dioxide. It will determine whether individual plants show variation in growth and reproduction under low and high carbon dioxide and examine the response of populations to selection for increased reproduction under low and high carbon dioxide. It will test to see whether such selection produces plants with an adaptive advantage and determine what physiological and developmental processes are associated with evolution of plants in response to carbon dioxide. This research will increase our understanding of the processes by which plants adapt to changing carbon dioxide levels over geologic time, and improve our ability to predict and understand the changes that plants may undergo due to human-caused changes in atmospheric carbon dioxide levels.
