A fundamental puzzle in evolutionary biology is whether evolution is repeatable: if many identical starting populations were exposed to the same type of novel environment, would they all evolve the same adaptations? Would the adaptations result from changes in the same underlying genes? This research project aims to answer both questions using a small fish, the threespine stickleback, as a study subject. The same ocean-dwelling form of stickleback colonized many separate river basins when the glaciers melted ~12,000 years ago, providing a naturally occurring experiment to test the repeatability of evolution. The researchers will measure environmental, morphological, and genetic divergence between adjacent lake and stream populations of stickleback, from each of 16 watersheds that represent separate instances of evolved lake-stream differences. They will then apply state-of-the-art statistical analyses to measure the extent to which differences between lake and stream types have evolved repeatedly or are unique to each watershed. Genetic analysis will reveal the extent to which repeated morphological differences result from evolutionary changes in the same genes.
The project will reveal general principles of how predictable evolutionary change is, and pioneer relevant statistical methods. Such principles and methods are vital to anticipating how pests or diseases may evolve in response to pesticides or drugs, or how species will adapt to climate change. In addition, the project will pair up leading biological researchers with high-school biology teachers and pre-service teachers-in-training, giving K-12 science teachers practical research experience involving fundamental principles of evolutionary biology.
