Dissertation Research: The Pattern and Process of Evolutionary Diversification: Lessons from an Alaskan Threespine Stickleback Radiation

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Postglacial threespine stickleback fish represent one of our most enlightening cases of biological diversification in nature. This study sheds light on the process through which postglacial stickleback populations originate and the factors responsible for the differences that exist among them. First, the evolutionary trajectory of a recently established lake population, derived from an oceanic form similar to the one that founded the broader regional adaptive radiation, will be evaluated. Issues addressed include how quickly lake isolates can diverge from their oceanic ancestors, the form evolutionary trajectories take in nature and the influence ancestral variation has on those trajectories. Then, the relative importance of gene flow and natural selection on phenotypic divergence within the broader regional adaptive radiation will be evaluated by applying traditional and novel methods of geographical analysis on a diverse stickleback lake-stream radiation in Cook Inlet, Alaska. This study combines powerful morphometric, molecular and geographical methods, and builds on decades of accumulated resources related to threespine stickleback ecology and evolution, to empirically examine microevolutionary processes in nature. The issues addressed are critical for understanding the origin and maintenance of biodiversity and provide criteria for conserving divergent populations.