B.S., 2000, University of Illinois
Ph.D., 2007, University of Minnesota
Postdoctoral Fellow, U. Toronto, 2007-9
Mutualism coevolution: evolutionary and ecological genetics of plant-microbe interactions; evolutionary responses to global change
My research focuses on the evolution of mutualisms, which are most generally defined as species interactions that increase the fitness of both (or all) partners. Mutualisms are ubiquitous! And they include some of the most important species interactions in nature (for example: mitochondria, mycorrhizae, gut endosymbionts). Though, at first impression, these friendly interactions might appear tightly coevolved, instead they may be characterized by temporal and spatial heterogeneity, cheating, even evolutionary instability.
I try to take a multidisciplinary approach and use diverse methods that traditionally are associated with the fields of quantitative genetics (multivariate statistics, greenhouse experiments), population and molecular genetics (genotyping, sequence analysis, expression assays), and ecology (field manipulations, collections) to understand multiple aspects of the evolution of mutualisms.
Some questions currently motivating my work include: 1. Under what conditions (including the abiotic and biotic environment) do mutualisms evolve, remain stable, or break down? 2. How phenotypically and genetically variable are mutualistic interactions, and why is such variation maintained, despite selective pressure to cheat or, alternatively, to remain honest? 3. Which genes are variable in nature, and which are, or have been, important players in coevolution?
Most generally, I am interested in plants, microbes, and their sundry interactions. Most of my research focuses on the interactions between legumes and their symbiotic nitrogen-fixing bacteria, called rhizobia. This includes the Medicago-Sinorhizobium mutualism because it is a great genetic model with an interesting ecology. I also have interests/projects in: the agronomically-important soybean-Bradyrhizobium interaction, invasive/naturalized clover-rhizobium interactions, invasive/naturalized Medicago lupulina-Sinorhizobium interactions, and the native prairie legume Chamaecrista fasciculata and associated rhizobia.
Heath KD. 2009. Intergenomic epistasis and coevolutionary constraint in plants and rhizobia. Evolution, in press.
Heath KD and P Tiffin. 2009. Stabilizing mechanisms in a legume-rhizobium mutualism. Evolution 63: 652-662.
Stinchcombe JR, Weinig C, Heath KD, Brock MT and Schmitt J. 2009. Polymorphic genes of major effect: consequences for variation, selection, and evolution in Arabidopsis thaliana. Genetics 182: 911-922.
Samis KE, Heath KD, and JR Stinchcombe. 2008. Discordant longitudinal clines in flowering time and PHYTOCHROME C in Arabidopsis thaliana. Evolution 62: 2971-2983.
Heath KD and P Tiffin. 2007. Context-dependence in the coevolution of plant and rhizobium mutualists. Proceedings of the Royal Society of London B 274: 1905-1912.