Which statement best describes hybrid vigor?

Which statement best describes hybrid vigor?

• A. The superior fitness of homozygous offspring as compared with that of their dissimilar heterozygous parents.
• B. The practice of selecting for desired color traits.
• C. The tendency for hybrid vigor to decrease with inbreeding.
• D. The improved or increased function of any biological quality in a hybrid offspring.

Answer: (D)

Hybrid vigor, or heterosis, is when a hybrid offspring shows improved performance for traits such as growth, yield, or disease resistance compared with its parents. The statement that best captures this idea says there is an improved or increased function of any biological quality in a hybrid offspring. This reflects how crossing genetically diverse parents can bring together beneficial alleles and mask deleterious ones, leading to superior performance in the hybrid. The other descriptions miss the essence: one talks about superior fitness of homozygous offspring, which isn’t what hybrid vigor describes (vigor usually appears in the heterozygous hybrid). Another refers to selecting for color traits, which is about appearance rather than functional improvement. The last notes that vigor can decrease with inbreeding, which is a consequence of reduced heterozygosity, not the defining feature of hybrid vigor itself.

Hybrid vigor, or heterosis, is when a hybrid offspring shows improved performance for traits such as growth, yield, or disease resistance compared with its parents. The statement that best captures this idea says there is an improved or increased function of any biological quality in a hybrid offspring. This reflects how crossing genetically diverse parents can bring together beneficial alleles and mask deleterious ones, leading to superior performance in the hybrid.

The other descriptions miss the essence: one talks about superior fitness of homozygous offspring, which isn’t what hybrid vigor describes (vigor usually appears in the heterozygous hybrid). Another refers to selecting for color traits, which is about appearance rather than functional improvement. The last notes that vigor can decrease with inbreeding, which is a consequence of reduced heterozygosity, not the defining feature of hybrid vigor itself.