Evolutionary tradeoffs as opportunities to improve yield potential

Photosynthetic efficiency and stress tolerance are examples of traits that had been improved by natural selection for millions of years prior to domestication of crops. Further improving such traits often requires accepting tradeoffs that would have reduced fitness of the crop's ancestors where they evolved. For example, improvements in yield potential have mostly come from reversing past selection for individual-plant competitiveness that conflicted with plant-community efficiency, or from tradeoffs between adaptation to past versus present conditions. A brief review of cold- and drought-tolerance did not find evidence of tradeoff-free improvements in crops, relative to wild ancestors. Identifying evolutionary tradeoffs that impose minimal agronomic tradeoffs can point the way to further improvements in yield potential and other community-level traits, perhaps including weed suppression. Crop genotypes that benefit subsequent crops merit more attention. Radical innovations never tested by natural selection may have considerable potential, but both tradeoffs and synergies will often be hard to predict.