Introgressive hybridization, or introgression, refers to the process of interspecific genetic transfer by means of backcrossing. Backcrossing is the process of a hybrid species crossing with one of the parent species of the hybrid (Figure 1).
Introgression creates variety within the gene pool of a species, facilitating adaptive radiation that allows organisms to fulfill open niches in a changing environment.'
Hybridization vs. Introgressive hybridization
- Hybridization involves the combination of two parent species, resulting in an even assortment of genes from both parent species.
- Introgressive hybridization involves an intricate combination of genes between a hybrid species and one of the hybrid's parent species, resulting in an imbalanced mixture of genes in the progeny due to a larger proportion of genes having been contributed by the original parent species that has backrossed with the hybrid.
Natural vs. Artificial IntrogressionEdit
Introgression occurs naturally, for example through cross-pollination of plant species.
Artificial introgression occurs through human-directed breeding, often to produce different phenotypes (Figure 2) or to obtain a desired genotype for agricultural purposes (Figure 3) .