New species form when characters evolve that reduce or prevent mating between populations. This process of speciation is critical to understanding the origins of biodiversity, yet little is known about the evolution of reproductive barriers at the earliest stages of divergence. While early models of speciation stressed the importance of geographic isolation to initiate divergence, recent theory suggests that ecologically-based natural selection is capable of driving isolation in the absence of geographic barriers. By focusing on a diverse complex of classically described, closely-related plants that remain distinct despite apparent hybridization, this research will utilize greenhouse, laboratory, and field experiments to investigate the evolutionary mechanisms and genomic changes that drive the early stages of speciation. Moreover, results from the experiments outlined in this proposal will generate novel insight into the role of ecologically-based divergent natural selection during speciation. The broader impacts of this research lie in its mentorship and educational opportunities. The broad array of techniques that will be employed, including field work and newly developed population genomic methods, will provide students with considerable experience in plant evolutionary research. Students from the UO Summer Program for Undergraduate Research, a program committed to recruiting and mentoring students from traditionally underrepresented backgrounds, will be a critical component for this research. In addition, this research will also be shared through public lectures with the California Native Plant Society, of which the co-PI is a member.
