As most alleles code for different versions of a protein or enzyme, having two different versions of this allele amounts to having two different versions of the enzyme. This increases the likelihood of an optimal version of the enzyme being present and reduces the likelihood of a genetic defect. The advantages of species hybridization are 1.) evolution of new interspecific breed, 2.) hybrid vigour, and 3.) enhanced longevity and immunity to diseases (Dubey, A. 2019). Dubey explains each as follows: 1.) A new interspecific breed is due to the mating of two distinguished species. 2.) Hybrid vigour is defined as a species becoming sturdier, more dynamic, and stronger than the parents. Lastly, 3.) Hybrids can have improved longevity and are “highly immune to diseases” (Dubey, A. 2019). Disadvantages The main advantage of F1 hybrids in agriculture is also their drawback. When F1 cultivars are used as parents, their offspring (F2 generation) vary greatly from one another. Some F2s are high in homozygous genes, as found in their grandparents, and these will lack hybrid vigour. From the point of view of a commercial seed producer who does not wish customers to produce their own seed via seed saving, this genetic assortment is the desired characteristic. Both inbreeding and crossing the ancestral lines of the hybrid are costly, because of the time and number of generations involved, which translates into a much higher price. Not all crop species exhibit a sufficiently high heterosis effect to offset this disadvantage. F1 hybrids mature at the same time when raised under the same environmental conditions. They all ripen simultaneously and can be more easily harvested by machine. Traditional cultivars and landraces are often more useful to gardeners because they crop over a longer period of time, avoiding gluts or food shortages. In contrast, the limitations can be due to genetic extinction and/or outbreeding depression. Dubey explains that genetic extinction can be caused by "hybrid swarms" noting the various degrees of hybrids. Outbreeding depression is the "cross between genetically distant populations" causing hybrids to reduce fit and isolation leading to reduced reproduction. See also Backcrossing Heterosis ("hybrid vigour") Heirloom plant References External links Agronomy Classical genetics Plant reproduction Pollination management Breeding