Heterosis in F2 Generation

Heterosis observed in the F2 generation (obtained by inter-se mating of F1) becomes:

Correct Answer: Half of F1 Generation

From the notes (Heterosis section): At each generation, heterozygosity is reduced by 50% — therefore heterosis also reduces by 50% per generation when F1 animals are inter-se mated.

Key Points on Heterosis (from notes)

• Heterosis = increase in performance of offspring over parents
• Depends on: (1) extent of heterozygosity and (2) non-additive gene action (Dominance + Over-dominance + Epistasis)
• Traits with low h² show high heterosis (reproductive traits — fertility, litter size, hatchability)
• Maximum hybrid vigour is in F1 generation
• Heterosis in F2 = ½ of F1 (due to inter-se mating)
• Commercially used in broiler, layer, swine and sheep production (high fertility)

Practical Application

This is why commercial producers do not breed F1 crossbreds together — they always produce fresh F1 hybrids to capture maximum heterosis.