Applying Both Landscape Genomic and Ecological Niche Model Predictions to Inform Conservation Strategies of a California Foundational Oak Species

Environmental factors shape the distributions of organisms and their underlying patterns of genetic variation. When climate changes rapidly, organisms that are adapted to current environments may become maladapted to future climates. Long-lived tree species are especially susceptible to climate maladaptation due to their sessile nature and long generation times. Understanding how foundational tree species will respond to future climate, both in adaptive ability and distribution shifts, is imperative for effective management and conservation of tree populations and the ecosystems they comprise. Here, we used whole genome sequences from 163 individuals of blue oak (Quercus douglasii) to determine predicted adaptedness, the degree to which an organism can survive and reproduce in future climate, based on landscape genomic models, compare those genomic predictions with ecological niche model predictions, and propose seed sourcing and restoration site strategies to increase the adaptedness of stands at preserves managed by The Nature Conservancy. Both ecological and genomic models predict that blue oak stands will be more susceptible to future climate along the Sierra Nevada basin, with patches of higher climate adaptedness along the central coast of California. To test whether management practices could increase adaptedness of blue oak stands, we examined the impact of seed source and restoration site choice on future stands. Regardless of restoration site category, our expectation held true that future maladaptation risk is reduced the most when using seed sources preadapted to the future climate of the restoration site. However, restoration sites containing stands with high habitat suitability and high climate adaptedness always did best. We conclude that strategic conservation and management strategies utilizing seed transfer from climate-adapted stands may improve the future health of blue oak stands susceptible to future climate.