Description of Quantitative Traits

Genetic and Environmental Effects

Quantitative Traits Statistics

Variance Components


Estimating Offspring Phenotype

Predicting Selection Response

Study Questions

Quantitative Genetics Overheads

Quantitative Genetics WWW Links

Genetic Topics

Estimating the Offspring Phenotype

If we have determined the narrow sense heritability of a trait and know several population values we can estimate the phenotypic value for an offspring. The following formula can be used for the prediction.

To = T + h2(T*-T) where

To = predicted offspring phenotype
T = population mean
h2 = narrow sense heritability
T* = midparent value [(Tf + Tm)/2]

Let's use the following information to estimate the offspring phenotype

T = 80 seeds/plant
Tf = 90 seeds/plant
Tm = 120 seeds/plant
T* = (90 +120)/2 = 105
h2 = 0.5


To = 80 + 0.5 (105-80)
To = 80 + 12.5
To = 92.5 seeds/plant

The conclusion that we can draw is not that each plant in the next generation will have 92.5 seeds/plant, but rather that on average the population derived from mating these two parents will have 92.5 seeds/plant. Remember that quantitative traits are affected by the environment, and the environment will be responsible for the deviations that we would see from the estimated phenotype.

Copyright © 1997,1999. Phillip McClean