Does heritability change across species, breeds, and populations?

Does heritability change across species, breeds, and populations?

• A. Only in crossbreeding
• B. Yes
• C. Only for some traits
• D. No

Answer: (B)

Heritability is context-dependent: it represents the proportion of phenotypic variation that is due to genetic variation within a specific population in a given environment. That ratio depends on both how much genetic variation exists for the trait and how much environmental variation affects the trait in that population. Because genetic makeup (allele frequencies, gene effects) and environmental conditions vary across species, across breeds, and among populations, the balance between genetic and environmental influences changes. In a very uniform environment, genetic differences contribute more to the observed differences, raising heritability; in a variable environment, environmental differences inflate phenotypes, lowering heritability. Crossbreeding and population structure can also alter the amount of additive genetic variance and the way genes interact with the environment, further changing estimates. So heritability can indeed change across species, breeds, and populations.

Heritability is context-dependent: it represents the proportion of phenotypic variation that is due to genetic variation within a specific population in a given environment. That ratio depends on both how much genetic variation exists for the trait and how much environmental variation affects the trait in that population. Because genetic makeup (allele frequencies, gene effects) and environmental conditions vary across species, across breeds, and among populations, the balance between genetic and environmental influences changes. In a very uniform environment, genetic differences contribute more to the observed differences, raising heritability; in a variable environment, environmental differences inflate phenotypes, lowering heritability. Crossbreeding and population structure can also alter the amount of additive genetic variance and the way genes interact with the environment, further changing estimates. So heritability can indeed change across species, breeds, and populations.