Hybridization (mating and cross-fertilization between different species) is a widespread natural phenomenon, yet its role in evolution is still debated. Is it a maladaptive force, usually resulting in sterile, dead-end individuals like mules? Or does it regularly contribute to adaptation and evolutionary diversification? A novel approach is proposed that compares long-term evolutionary change in experimental hybrid and non-hybrid control lines in the field. The hybrid lines, intended to recreate the early stages of an ancient natural hybridization, are derived by crossing the parents of a well-studied wild sunflower. Whether hybridization can increase rates of adaptation and phenotypic change will be examined by tracking fitness, traits, and quantitative trait loci (QTL) in the hybrid and control populations over 5-10 generations. Evolutionary change will be distinguished from phenotypic plasticity by comparing the lines in common gardens. The long-term predictability of change in hybrid systems will be examined by assessing whether the experimental hybrids converge phenotypically and genotypically on the natural hybrid upon which they are modeled.
The proposed research is the first experimental field study to examine the impact of hybridization on adaptive evolution over multiple generations in a wild (non-crop) system. The research supported by this grant will impact science education at the K-12 and university levels, through annual outreach programs and a sunflower teaching module for elementary school students. The project will integrate research and education by training ten undergraduate students, three graduate students, and two technicians. Based on the current population of the PI's lab, more than half of the students participating in this grant will be from underrepresented groups in the sciences.
