Research Interests
I am broadly interested in understanding the processes that promote and limit adaptive evolution in natural plant populations.  I have been particularly interested in how broad-scale spatial and temporal variation in ecological factors influences the evolution of functionally-important traits.  My work concentrates on two types of interactions between plants and their biotic communities.  First, I am examining the ecological and genetic factors that facilitate the evolutionary transition between outcrossing and self-fertilization, which has occurred repeatedly in plants.  This line of research includes field studies of plant-pollinator interactions and molecular genetic studies of populations that differ in mating system.  Second, I am investigating the long-term evolutionary dynamics of plant defense against pathogens and herbivores using sequence data from natural plant populations.  Both research areas explicitly consider the geographical context of the evolution of species interactions.  An exciting new research direction examines the evolutionary limits on species’ geographic ranges.  This work addresses the complex problem of why species fail to adapt to conditions outside their current distribution and consequently maintain stable range limits.  My work has focused on annual plant species in the genus Clarkia (Onagraceae) in the Sierra Nevada of California, and the wild relatives of maize in the genus Zea (Poaceae), which are endemic to Mexico.  Although my work has concentrated on plant species, I am interested in exploring fundamental questions in evolutionary biology and ecology across a diverse array of systems.