What is hybrid vigor or heterosis?

Hybrid vigor, also known as heterosis, refers to the phenomenon where the offspring resulting from the crossbreeding of two different genetic lines exhibit improved or enhanced characteristics compared to their parents. This can manifest in various traits such as growth rate, fertility, health, and overall fitness.

When two genetically diverse parents are crossed, their offspring often inherit a combination of advantageous traits, leading to enhanced performance. This is particularly important in agriculture, where hybrid crops and livestock can show significant improvements in yield and resilience. The underlying principle involves the increased genetic diversity that comes from combining different gene pools, which can mask deleterious alleles and bring out superior traits.

In contrast, the other options describe concepts that do not accurately represent hybrid vigor. For instance, inheriting traits from grandparents does not result in the enhanced capabilities associated with hybrid vigor. Similarly, being genetically identical would imply no hybridization has occurred, and offspring with decreased fertility contradict the fundamental benefits of hybrid vigor. Therefore, the correct answer emphasizes the superiority in performance of the offspring due to the advantageous genetic contributions from both parent lines.