Oysters’ Survival in Changing Environments
How organisms optimize fitness across variation in the environment is a complex, multi-level process. To predict the evolutionary capacity of populations in response to changing environments, it is important to understand interactions between phenotypic plasticity (the ability of an individual to adjust phenotype for a better fit to the environment) and evolution of local adaptation at the population level.
Matthew P. Hare, Natural Resources, and his collaborators are studying these processes in a species—eastern oysters (Crassostrea virginica)—that experiences extreme habitat variation at local spatial scales and temporally with every tide. The team is testing the hypothesis that trait variation generated by strong selection across environmental gradients is greater than what phenotypic plasticity could produce. Oysters have a suite of characteristics, including high fecundity, broad larval dispersal, and minimal habitat choice, predicted to make selection a strong diversifying force every generation.
The team is focusing on eastern oysters in Delaware Bay and their variable tolerance to low salinity water after rain. This native oyster is commercially valuable and an important ecosystem engineer, providing estuarine habitat for hundreds of invertebrate and fish species. Laboratory challenge experiments and whole genome sequencing will be used to identify the genetic architecture underlying low salinity tolerance variation. Then, the spatial and temporal impacts of selection will be inferred based on wild oyster genotyping. The study will provide new insights on factors that control oyster survival and growth in estuaries, improve understanding of mechanisms that shape the realized larval dispersal connecting subpopulations, and contribute to optimization of both commercial aquaculture and hatchery-based restoration of wild populations.