Question

You cross a true breeding tomato plant with large fruits to a true breeding plant that has small fruits. All of the F1 offspring have medium sized fruits, with a variance in fruit size of 0.06 cm2 . When you create F2 plants, the variance in fruit size is 0.60 cm2 . What is the broad sense heritability (H2 ) of fruit size?

Answer 1

Answer:

H² = 0.9

Explanation:

Phenotypic variance (VP) = genetic variance (VG) + environmental variance (VE)

The observed VP in the F1 is composed only of VE, because the parents were true breeding (thus VG=0).

The F2 variance is due to both genetic and environmental variation. If the tomato plants are in the same environment, the VE wil be the same, and then we can calculate VG as:

VG = VP - VE

VG = 0.60 cm² - 0.06 cm²

VG= 0.54 cm²

Broad sense heritability is calculated as: H² = VG/VP. It is used to describe how much of the observed phenotypic variation is due to genetic variation (comprised by additive, dominance and epistasis variance).

In this case,

H² = VG/VP

H² = 0.54 cm² / 0.60 cm²

H² = 0.9