What is the phenomenon of heterosis?

The phenomenon of heterosis is an increased productivity of distant hybrids.
Heterosis is a phenomenon of “hybrid strength.” By heterosis, we understand the superiority of the first generation offspring over parental forms in terms of vitality, endurance, productivity, arising from the crossing of different races, animal breeds, etc. The phenomenon of heterosis depends on the degree of kinship between the parental individuals: the more distant relatives the parental individuals are, the more pronounced the effect of heterosis in first-generation hybrids.