PARENT SESSION
Oral Session #60: Agroecology- Sustainable Agriculture.
Presiding: R. Bohanan
Wednesday, August 7. 8:00 AM to 11:30 AM. Mesquite Room, Radisson.
Darwinian agriculture: when can humans find solutions beyond the reach of natural selection?
Denison, R. Ford*,1, Kiers, E. Toby1, West, Stuart2, 1 Agronomy and Range Science, Davis, CA, 956162 Institute of Cell, Animal & Population Biology, Edinburgh, UK
ABSTRACT- Never underestimate the power of natural selection, but remember that it does not share our goals. 1) Natural selection acts on genes, individuals, and families, but not on communities or ecosystems. Unless there is some other natural process that consistently improves ecosystem structure, the structure of any given natural ecosystem may be far from optimal, especially by criteria relevant to agriculture. Mindless mimicry of natural ecosystems is a bad idea. Studying positive and negative relationships between structure and function of natural ecosystems may nevertheless provide insights for the design of agricultural ecosystems. Deploying the available crop diversity in ways not seen in nature (e.g., crop rotation rather than intercropping) may present a greater challenge to agricultural pests. 2) Natural selection had millions of years to test alternative solutions to problems that consistently limited the fitness of individual plants. When natural selection repeatedly found the same solution -- C4 photosynthesis, a solution to photorespiration, has evolved >30 times -- it is likely that any better solution is so novel as to be beyond current human ingenuity. The most important opportunities for genetic improvement in crop yield potential will involve tradeoffs between adaptation to current vs. past environments, or between the competiveness of individual plants and the collective performance of plant communities. 3) The short-term evolution of mutualistic symbioses important to agriculture deserves greater attention.
KEY WORDS: natural selection, crop genetic improvement, agroecosystem design