Extending Darwin’s Analogy: Bridging Differences in Concepts of Selection between Farmers, Biologists, and Plant Breeders1

based on an analogy between selection by plant and animal breeders of his day and what he termed “natural selection,” or more generally “selection.” “Natural selection” or “selection” for Darwin included what biologists came to see as being composed of (1) phenotypic selection of individuals based on phenotypic differences, and, when these are based on heritable genotypic differences, (2) genetic response, or a change in the genetic structure of a population between generations resulting from a greater contribution of the selected individuals, and which results over generations in (3) evolution (cumulative, directional genetic response). Biologists’ and plant breeders’ use of the terms “selection” and “natural selection” continues to be influenced by an emphasis on evolution. They use a linguistic synecdoche, where “selection” or “natural selection” represents the whole process of evolution, reflecting a prevailing assumption in the common use of the term “selection” in biology and plant breeding—that phenotypic selection is only biologically significant when it results in evolution. (Unless otherwise indicated, we use the terms “selection” and “phenotypic selection” synonymously to refer to phenotypic selection with no implication that it results in genetic response.) Extending Darwin’s analogy of natural selection with artificial selection by amateur plant and animal breeders to an analogy with traditional farmers’ crop management illustrates how selection can have important ecological and agronomic functions when it does not result in any genetic response, or can lead to short-term intergenerational genetic change (genetic response), in addition to longer-term directional change or evolution. Evidence that farmers’ concepts of selecExtending Darwin’s Analogy: Bridging Differences in Concepts of Selection between Farmers, Biologists, and Plant Breeders1