Diana Pilson
Diana Pilson
Associate Professor

Ph.D Duke University, 1990
Contact Information
408A Manter Hall

Research Interests

I am an evolutionary ecologist -- I study both the ecological factors that cause natural selection and the genetic basis of ecologically important traits. Using manipulative field experiments and quantitative genetic methods, I hope to understand constraints on response to natural selection. Together with my graduate students and collaborators at other universities I am involved in three ongoing projects.

Ongoing Projects

1) Evolution of response to herbivory in wild sunflower, Helianthus annuus. In response to insect damage plant populations may evolve either resistance (characters that reduce the amount of damage) or tolerance (characters that reduce the impact of damage on plant fitness). However, tolerance, and constraints on the joint evolution of resistance and tolerance, are relatively poorly understood. Using quantitative genetic methods we are evaluating predictions of theoretical models, as well as describing mechanisms of tolerance of insect damage.

2) Evolutionary and ecological consequences of the escape of transgenes into wild populations. Because commercial sunflower is host to a number of economically important insect pests, several seed companies are developing transgenic varieties. Wild Helianthus annuus and commercial sunflower are the same species and are completely interfertile. Thus, if transgenic varieties are released commercially it is likely that the transgenes will escape (via pollen flow to wild plants) into wild populations. We are examining the fitness effects of a Bt transgene in a wild background, as well as the potential effects of this transgene on sunflower population dynamics and insect community structure within sunflower heads.

3) Evolution of the sex ratio, mating system, and sexual dimorphism in Croton texensis, an annual in the Euphorbiaceae. Croton is dioecious (but rare hermaphrodites occur), it has a sex ratio that fluctuates among years from female to male biased, and it is sexually dimorphic for several morphological characters. For these reasons Croton is ideally suited for examining the evolution of plant mating systems.


  • Pilson, D., N. Pleskac, and E. J. Sundvall. (submitted) Evaluating the importance of interspecific competition among seed herbivores of wild sunflower (Helianthus annuus). Ecological Entomology.
  • Snow, A.A., D. Pilson, L. Rieseberg, M. Paulsen, N. Pleskac, M. Reagon, D. Wolfe, S. Selbo. 2003. A Bt transgene reduces herbivory and enhances fecundity in wild sunflowers. Ecological Applications (in press).
  • Pilson, D. and K.L. Decker. 2002. Compensation for herbivory in wild sunflower: response to simulated damage by the head-clipping weevil. Ecology 83:3097-3107.
  • Snow, A.A., D. Pilson., L. H. Rieseberg., and H. M. Alexander. 2002. Ecological effects of pest resistance genes that disperse into weed populations. In: Proceedings of the 7th International Symposium on The Biosafety of Genetically Modified Organisms, October 2002 Beijing. (http://www.worldbiosafety.net/)
  • Pilson, D., A. A. Snow, L. H. Rieseberg, and H. M. Alexander. 2002. Fitness and population effects of gene flow from transgenic sunflower to wild Helianthus annuus. In: Proceedings of a Workshop on the Ecological Effects of Transgenic Crops, March 2002, Columbus, OH (http://www.biosci.ohio-state.edu/~lspencer/gene_flow.htm)
  • Pilson, D. 2000. The evolution of plant response to herbivory: simultaneously considering resistance and tolerance in Brassica rapa. Evolutionary Ecology 14:457-489. (Invited as part of special feature on the ecology and evolution of tolerance of insect damage; published in July 2001)
  • Pilson, D. 2000. Flowering phenology and resistance to herbivory in wild sunflower, Helianthus annuus. Oecologia 122:72-82. (highlighted in January 29, 2000 issue of New Scientist)
  • Decker, K.L. and D. Pilson. 2000. Environmental sex determination as a possible cause of biased sex ratios in Croton texensis. American Journal of Botany 87:221-229.
  • Snow, A.A., H. Alexander, J. Caroline, S. Louda, D. Pilson, C. Roseland, G. Seiler, D. Shanahan, and J. Wolt. 1999. Report of the Sunflower Working Group. In: Proceedings of a Workshop on Ecological Effects of Pest Resistance Genes in Managed Ecosystems, January 31-February 3, 1999 (P.L. Traynor and J.H. Westwood, editors). Information Systems for Biotechnology, Virginia Polytechnic Instititute and State University, Blacksburg, VA.
  • Snow, A.A., L.H. Rieseberg, H.M. Alexander, C. Cummings, and D. Pilson. 1999. Assessment of gene flow and potential effects of genetically engineered sunflowers on wild relatives. Proceedings of the 5th International Biosafety Symposium, Branschweig, Germany.