About the Department

Faculty

Graduate Program

Undergraduate Program

Courses

Seminars and Events

Useful Links

Resources

Employment Opportunities



EEB Home

Contact Information:

Phone: (612) 625-5700
Fax: (612) 624-6777
Email: wiggins@umn.edu

University of Minnesota
Ecology, Evolution, and Behavior
100 Ecology Building
1987 Upper Buford Circle
St. Paul, MN 55108

Department Contacts
Support Staff
Research Associates
Department Directory

R. Ford Denison

Adjunct Professor, Dept. of Ecology, Evolution, and Behavior

Ph.D., Cornell University, 1983

Contact Information

Graduate Faculty Memberships

Ecology, Evolution and Behavior, Plant Biological Sciences

Research Interests

Evolution of mutualism (especially legumes and rhizobia); implications of past and ongoing evolution for agriculture.

Statement

How does evolution based on "selfish genes" maintain cooperation? We are trying to answer this question for rhizobia, symbiotic bacteria that infect legume plants like alfalfa or soybean and (to varying extents) supply them with nitrogen. Fixing nitrogen is costly for rhizobia, so why haven't rhizobia that supply their plant hosts with nitrogen (indirectly benefiting competing rhizobia infecting the same plant) been completely displaced by "ineffective" rhizobia? Why are ineffective rhizobia common enough to be a problem in some soils but not others? This research may lead to practical applications, such as legume crops that selectively enrich the soil with the most-beneficial local strains of rhizobia. This research may also be relevant to other cases where symbiosis breaks down, as in coral bleaching. As time allows, I also hope to explore other applications of modern evolutionary theory, pursuing some of the ideas in our paper on Darwinian Agriculture. To pursue my research objectives, I have often had to develop new tools, including mechanistic computer models and noninvasive scientific instruments, such as the nodule oximeter or a laser-scanner measure green leaf area index in the field.

Selected Publications

Kiers, E.T., R.A. Rousseau, and R.F. Denison. 2006. Measured sanctions: legume hosts detect quantitative variation in rhizobium cooperation and punish accordingly. Evolutionary Ecology Research 8:1077-1086.

R.F. Denison and E.T. Kiers. 2004. Lifestyle alternatives for rhizobia: mutualism, parasitism, and forgoing symbiosis. FEMS Microbiology Letters 237:187-193.

Martini, E.A., J.S. Buyer, D.C. Bryant, T.K. Hartz, and R.F. Denison. 2004. Yield increases during the organic transition: improving soil quality or increasing experience? Field Crops Research 86:255-266.

Kiers, E.T., R.A. Rousseau, S.A. West, and R.F. Denison. 2003. Host sanctions and the legume-rhizobium mutualism. Nature 425:78-81.

Kinraide, T.B., and R.F. Denison. 2003. Strong inference, the way of science. American Biology Teacher 65:419-424.

Denison, R.F., E.T. Kiers, and S.A. West. 2003. Darwinian Agriculture: When can humans find solutions beyond the reach of natural selection? Quarterly Review of Biology 78:145-168.

Denison, R.F., C. Bledsoe, M. Kahn, F. O'Gara, E.L. Simms,and L.S. Thomashow. 2003. Cooperation in the rhizosphere and the "free rider" problem. Ecology 84:838-845.

Denison, R.F. 2000. Legume sanctions and the evolution of symbiotic cooperation by rhizobia. American Naturalist 156:567-576.