Dissertation Research: Determining the Mechanisms of Recurrent Cline Evolution in White Clover (Trifolium repens)

Washington University, Saint Louis MO

Investigators

Abstract

Investigating the spatial and temporal scales of adaptation has proven difficult because the molecular basis of ecologically important traits is often complex. This project examines in white clover the process of adaptation using five independent geographical gradients in a well-characterized trait called cyanogenesis (cyanide release after tissue damage). Specifically, this work compares genetic variation throughout the clover genome to variation in the two genes underlying cyanogenesis, with the goal of understanding the degree to which natural selection, gene flow, and other processes are conserved across gradients. The origins of the adaptive variation in each gradient will also be investigated. Further, ecological experiments will be used to identify the ecological trade-offs that maintain cyanogenesis variation within populations. Understanding the processes that create and maintain ecologically important variation is fundamental in making predictions regarding species responses to changing environments and establishing future policy. This proposal investigates these processes in a tractable natural system. This work will answer broad questions about adaptation while providing a useful case study for predicting species responses. This proposal carries a large educational outreach component for undergraduates and high school students, using clover cyanogenesis as a basic teaching tool for understanding the connection between genetics and ecology. The project will also provide training to young scientists and high school teachers in laboratory and field settings.