Question

If a trait has no genetic variance in a population but still has phenotypic variance, its narrow-sense and broad- sense heritability are both equal to zero. (True or False)

Answer 1

False

Heritability (irrespective of being narrow sensed or broad sensed) presents an estimate of variation in the phenotypic trait in population of an organism that has arisen because of genetic variation between the individuals in that population.

Along with measuring phenotypic variation due to genetic variation, it also measures the phenotypic variations arising due to factors other than environment or random chance. Heritability accounts for variations arising out of non-genetic factors as well.

Narrow sense heritability talks about variations due to other than genetic factors or “additive factors” unlike the broad sense heritability which is because of genetic factors.

Thus, as the case given in the problem statement, the narrow sense heritability could not be zero for phenotypic variations arising due to other than genetic variations.