Collaborative Research: RUI: A longitudinal study of hybridization in Mimulus: revealing the ecological, phenotypic, and genetic determinants of porous species boundaries.

This research investigates how biological diversity is maintained between closely related species in a changing environment. The work focuses on two species of yellow monkeyflowers—ecologically diverse wildflowers common across North America—that frequently meet and interbreed to create hybrids. In a unique, multi-year study of natural populations in the Columbia River Gorge, this research will track how fluctuating environmental conditions, such as drought, influence whether these plant species interbreed or remain separate. By combining detailed field observations with advanced genetic analyses, the project will identify specific genes that help plants adapt to their surroundings and maintain species barriers. Understanding the genetic basis of reproductive barriers like flowering time is critically important for modern plant breeding and biotechnology. For example, knowledge from this work could lead to developing crops that are better synchronized with specific growing seasons or more resilient to climate-driven stressors like drought. Additionally, these projects will offer rich training experiences for undergraduate and graduate students who will be involved in all aspects of the research. The projects will also provide significant outreach opportunities, including public lectures, experimental demonstrations at the field sites, greenhouse tours, and engagement with high school students. The origin of species is usually shown as a simple splitting of one lineage into two, but hybridization is pervasive across the tree of life and can complicate the speciation process. This long-term study of naturally hybridizing yellow monkeyflower (Mimulus) species will reveal how interspecific gene flow affects the probability of adaptation and tempo of speciation. The evolutionary impact of hybridization depends critically on the rate of interspecific mating (pre-zygotic barriers) and the fitness of hybrids (post-zygotic barriers), and these factors, in turn, are often highly contingent upon the environment. The specific scientific objectives of this research are as follows: 1) Identify the environmental determinants of Mimulus ancestry structure in secondary contact zones across space and time. 2) Determine how reproductive barriers respond to environmental variation. 3) Identify the genetic basis of divergent ecological adaptation and assess how mapped barrier loci respond to fluctuating natural environments. 4) Discover the ecological context and genomic impact of hybridization across a broad geographic region. Completion of the aims in this proposal will provide an unprecedented view of the ecological variables, phenotypes, and genetic loci that determine the fate and evolutionary impact of hybridization. Additionally, this project includes several public outreach initiatives and provides unique cross-training opportunities for students at a Research 1 institution (University of Georgia) and a predominantly undergraduate institution (Reed College). This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2546336 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Andrea Sweigart | Institution: University of Georgia Research Foundation Inc, ATHENS, GA | Award Amount: $986,241 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2546336 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2546336.html