Collaborative research: RUI: a longitudinal study of hybridization in mimulus: revealing the ecological, phenotypic, and genetic determinants of porous species boundaries

The National Science Foundation Division of Environmental Biology awarded The Reed Institute $830,726 on August 1, 2026, under the Biological Sciences program (CFDA 47.074) to conduct a five-year longitudinal study of hybridization in yellow monkeyflower populations in the Columbia River Gorge near Portland, Oregon.

The research investigates how ecological, phenotypic, and genetic factors determine reproductive isolation between closely related plant species under fluctuating environmental conditions. The project tracks two species of yellow monkeyflowers—ecologically diverse wildflowers common across North America—that frequently interbreed in natural populations. By combining field observations with genetic analyses across multiple years, the work identifies specific genes that help plants adapt to their environment and maintain species barriers, particularly focusing on how drought and other environmental stressors influence interbreeding behavior and reproductive timing.

The project includes training and outreach components: undergraduate and graduate students participate in all research aspects, and the work provides public lectures, experimental demonstrations at field sites, greenhouse tours, and engagement with high school students. Understanding the genetic basis of reproductive barriers has applications for modern plant breeding and crop development, including crops better synchronized with specific growing seasons or more resilient to climate-driven stressors.

The period of performance runs from August 1, 2026, through July 31, 2031, with work performed in Portland, Oregon.

Abstract

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.- subawards are not planned for this award.