Grant: Discovery Grants Program - Individual

Natural selection is widely viewed as the principal evolutionary force shaping the diverse adaptations that make organisms so well suited to their physical and biological environments. Yet, scientists are still learning how selection interacts with other processes of evolution (mutation, genetic drift and gene flow) in complex natural habitats. This research addresses two enduring and unresolved problems in evolutionary biology. First, I will continue a productive investigation into the evolution of inbreeding, particularly self-fertilization in plants. While many organisms reproduce by mating with unrelated individuals, selfing has evolved thousands of times, with profound ecological and genetic consequences. I will also continue relatively new research to understand the evolution of geographical range limits. Virtually all organisms have limited distributions, which poses a difficult problem: why does natural selection not cause populations at the limits to adapt to local conditions and spread outward? Because these two problems involve interactions among the major evolutionary forces, thorough analysis can change our fundamental understanding of evolution. Both problems have been analyzed using mathematical models, but there is a clear need for experimental tests of these models. To this end, we will perform surveys of geographic variation, molecular-genetic assays, manipulative experiments in natural habitat and genetic experiments in controlled environments using a set of flowering plants proven to be exceptional experimental subjects. Our long-term goals are to better understand (1) how natural selection shapes reproductive behaviour; (2) how selection interacts with the other evolution processes; (3) the genetic and ecological constraints on adaptation; and (4) how evolutionary forces play out across multiple spatial scales. This research will help provide answers to fundamental questions in biology that can contribute to the conservation of rare species and the management of exotic invaders, and will train graduate and undergraduate students in valuable and transferable skills such as (i) modern genetic techniques, (ii) field biology in a variety of ecosystems, and (iii) experimental design and recent advances in statistical analysis.