What is the phenomenon called when heterozygotes possess greater vigor than either of the homozygotes?

The phenomenon where heterozygotes exhibit greater vigor, growth, fertility, or other beneficial traits compared to either homozygote is known as heterosis. This concept, often referred to as hybrid vigor, arises from the genetic diversity and combination of alleles present in heterozygous individuals. Heterosis can lead to improved traits such as enhanced disease resistance, better survival rates, and increased productivity in agricultural contexts, particularly in livestock breeding.

Heterosis is particularly important in beef production, where breeding programs often select for hybrid animals that can outperform their purebred counterparts. This improvement in performance is linked to the increased genetic diversity that allows for a more advantageous expression of traits in offspring. As a result, understanding heterosis is crucial for breeders aiming to optimize herd performance and sustainability.

In contrast, heterozygous advantage refers more broadly to situations in which heterozygotes provide a survival benefit in a specific environmental context, while the dilution effect pertains to the reduction in population or species dominance due to the introduction of new individuals. Genetic drift involves random changes in allele frequencies, especially in small populations and does not directly relate to the vigor of heterozygotes.