Genetic analysis of coevolution between plants and their natural enemies.

Plants exhibit a diverse array of characteristics that have been interpreted as functioning primarily as defenses against natural enemies, such as pathogens and herbivores. Recent genetic analyses of resistance provide evidence supporting this interpretation. In addition, these analyses also support a key assumption underlying models of the evolution of resistance (i.e. that resistance is costly) and suggest that the outcome of coevolution is often not explainable in terms of pairwise interactions between a plant and individual natural enemies (i.e. coevolution is often likely to be diffuse rather than pairwise).