Does introgression of crop alleles into wild and weedy living populations create cryptic in situ germplasm banks?

Natural gene flow often delivers alleles from cultivated species into unmanaged populations of weedy or wild relatives. Unmanaged populations with introgressed crop alleles may become the unintended repositories of crop alleles that are no longer available to breeders. Descriptive studies have confirmed the introgression of alleles from 17 crop species into free‐living populations. Multigeneration experimental studies allowing hybrid‐derived individuals to evolve under natural conditions are informative, but remain few. A study in this issue of Molecular Ecology (Molecular Ecology, 26, 2017) documents genomewide crop allele evolution in experimental populations of crop‐wild hybrid‐derived sunflowers. Approximately, three‐quarters of the wild alleles increased in frequency;—however, 5% of the crop alleles in each of the two sites increased (Molecular Ecology, 26, 2017; Figure 1). The remainder behaved as if they were neutral. This study's results plus those of prior studies demonstrate that introgressed populations of crop‐wild relatives contain a mixture of wild and crop alleles and thereby can be valued as a distinct kind of in situ germplasm resource relative to nonintrogressed populations.