It is well known that climate change is rapidly altering polar habitats. However, it is largely unknown how organisms in those habitats will evolve and adapt in response to climate change. This hampers efforts to predict future changes in marine ecosystems. This research will examine how diatoms, an important group of plankton in the Southern Ocean, adapt to environmental change. During a research cruise to the Southern Ocean, diatoms will be sampled from different regions of the Southern Ocean, including the Drake Passage, the Pacific Sector of the Southern Ocean and the Ross Sea. Samples will be processed to examine genetic diversity in the field. In the lab, evolution experiments will be conducted to measure the rates of adaptation to increasing temperature and ocean acidification. Data on the diversity of field populations combined with data on rates of adaptability will provide key insights into the "evolvability" of marine diatoms. This project will support a doctoral student and a postdoctoral researcher as well as several undergraduates. These scientists will learn the fundamentals of experimental evolution, a skill set that is sorely needed in the field of ocean climate change biology. The project also includes a collaboration with the Metcalf Institute for Marine and Environmental Reporting. The Metcalf Institute will design and implement a session focused on current research related to evolution and climate change to be held at the annual conference of the National Association of Science Writers (NASW). Although it is well understood that climate change is rapidly altering polar habitats, the evolutionary response of cold-adapted, biogeochemically important phytoplankton is essentially unknown and represents a major knowledge gap that hampers efforts to predict future changes at the base of the marine food web. Both physiological and genetic variation are key parameters for understanding evolutionary processes in phytoplankton but they are essentially unknown for Southern Ocean diatoms. The extent of these two factors in field populations (physiological and genetic variation) and the interaction between them will influence how and whether cold-adapted diatoms can respond to changing environments. This project is focused on diatoms and includes a combination of a) field work to identify genetic diversity within diatoms across the Drake Passage, the Pacific sector of the Southern Ocean and the Ross Sea, b) experiments in the lab to assess the range of physiological variation in contemporary populations of diatoms and c) evolution experiments in the lab to assess how the combination of genetic diversity and physiological variation influence the evolutionary potential of diatoms under a changing environment. This research will uncover general relationships between physiological variation, genetic diversity, and evolutionary potential that may apply across microbial taxa and geographical regions, substantially improving efforts to predict shifts in marine ecosystems under global change. Results from this study can be integrated into developing models that incorporate evolution to predict ecosystem changes under future climate change scenarios. This project will support a doctoral student and a postdoctoral researcher as well as several undergraduates. These scientists will learn the fundamentals of experimental evolution, a skill set that is sorely needed in the field of ocean climate change biology. The project also includes a collaboration with the Metcalf Institute for Marine and Environmental Reporting. The Metcalf Institute will design and implement a session focused on current research related to evolution and climate change to be held at the annual conference of the National Association of Science Writers (NASW).