Genetic variability in population responses of Atlantic cod to environmental change on a microgeographic scale

In the face of environmental change, the future of a species depends on the extent to which populations respond differently to changes in their environment and the spatial correspondence between the scale of disturbance and the scale of adaptation. Popula tions that are adapted to different environments are likely to respond differently to environmental change. We are interested in how populations of an economically and ecologically important marine fish, Atlantic cod, respond differently to environmental change and whether these differences exist at very small geographic scales. Along the coast of Norway, there are cod that live exclusively inside fjords, where the deep waters they inhabit are sheltered from seasonal temperature variations, and cod that l ive in coastal areas outside fjords, where the water is mixed such that deep waters experience a wider range of temperatures. We expect that these populations have evolved different responses to temperature because of the different environments they are e xposed to, as has been found for other cod populations on a broader geographic scale. Our main objectives are to: 1. Determine the responses of inner fjord and outer coastal cod populations to temperature by raising cod from these areas at various tempera tures in the lab; 2. Associate population differences in growth and survival responses at a very small spatial scale with changes in gene expression; and 3. Identify genes involved in these responses by comparing patterns of gene expression between popula tions. This project will impact the management of wild cod and the development of cod aquaculture by increasing our understanding of the genetic basis for responses to temperature, by identifying populations well suited to withstand environmental change a nd whose genetic diversity could be used to enhance aquaculture and fisheries, and by guiding management efforts to lower the potential for population collapse and biodiversity loss in the face of climate change.