Collaborative Research: RoL: Rapid Evolution of Reproductive Isolation via Hybrid Seed Lethality in Mimulus

North Carolina State University, Raleigh NC

Investigators

Abstract

The divergence of living forms into nine million different species depends on lineages becoming reproductively isolated. This reproductive isolation prevents interbreeding, allowing for the emergence of distinct species. This research project makes use of the tremendous species diversity present in the monkey flowers (Mimulus). Comparison of many pairs of species in this group will uncover the genetic changes responsible for and the evolutionary forces at work that generated reproductive isolation. Understanding the interactions between genetic mechanisms and evolutionary processes that lead to species diversification will also contribute to agricultural breeding programs. The project includes efforts to educate grade school and high school students about evolution and the value of species diversity, and train undergraduate and graduate students in evolutionary biology and the molecular genetics of development. This research project focuses on the evolution of F1 hybrid seed inviability, a relatively unstudied but potentially common reproductive barrier in flowering plants. This project integrates phylogenetic, population genetic, developmental, transcriptomic, and genome mapping approaches to systematically address whether hybrid seed failure is a key isolating mechanism driving population and species diversification across the genus Mimulus. The project will test the hypothesis that this form of reproductive isolation evolves rapidly via natural selection generated by parent-offspring conflict in all outbreeding flowering plant species. Such conflict-driven selection is expected to cause divergent evolution of the genetic control of endosperm development in seeds in different lineages via differential genomic imprinting, quickly leading to strong postzygotic isolation regardless of the ecological environments that the species experience. The main goals of this project are to determine the rate of evolution, strength, and importance of hybrid seed inviability in the speciation process across the genus Mimulus; to assess the developmental mechanisms and transcriptomic signatures of hybrid seed inviability, and finally to determine the genetic basis of hybrid seed inviability and the degree of parallelism in the genetic basis of speciation in this genus. 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.