Hétérosis

Hétérosis, also known as hybrid vigor, is a biological phenomenon where the offspring of two different varieties or breeds are superior to their parents in terms of size, growth rate, fertility, or yield. This superiority is typically observed in the first filial generation (F1) and may diminish in subsequent generations.

The underlying genetic basis of hétérosis is thought to be the masking of deleterious recessive alleles and the expression of beneficial dominant alleles. When two inbred lines, which are often homozygous for many genes, are crossed, the resulting heterozygote offspring can benefit from having a wider range of gene expression and potentially complementary gene interactions. This heterozygosity can lead to a broader and more robust phenotype.

Hétérosis is widely exploited in agriculture, particularly in the production of hybrid corn (maize), sorghum, and other crops. By carefully selecting and crossing parent lines with desirable traits, breeders can produce F1 hybrids that exhibit significantly higher yields, increased disease resistance, and improved stress tolerance compared to their parental varieties. This has been a cornerstone of modern agricultural productivity.

In animal breeding, hétérosis is also observed. Crossing different breeds of livestock, such as cattle, pigs, and poultry, can result in offspring with improved growth rates, reproductive efficiency, and overall health. However, maintaining purebred lines for crossing can be more complex and costly in animal production compared to plants. The extent of hétérosis can vary depending on the species, the genetic distance between the parent lines, and the specific traits being evaluated.