(introgressive hybridization) The incorporation of genes from one species or subspecies into another related species or subspecies. It arises as a result of successful hybridization and subsequent backcrossing of the hybrids with one of the parental populations. Introgression is believed to have been a major factor in the evolution of many plants, especially crop plants. For example, the present wide range of the sunflower (Helianthus annuus) over North America is thought to have been achieved fairly recently by the introgression of genes from a number of Helianthus species, each providing characteristics enabling adaptation to different environments. Introgression is the basis of some plant breeding techniques. Compare gene flow.  |
