PBG 650 Advanced Plant Breeding. Module 7: Estimating Genetic Variances Why estimate genetic variances? Single factor mating designs. Why estimate genetic variances?. New crop species ensure adequate genetic variance for selection determine appropriate type of cultivar
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PBG 650 Advanced Plant Breeding
Module 7: Estimating Genetic Variances
Why estimate genetic variances?
Single factor mating designs
Bernardo, 2010, Chapt. 7
Do Breeders Need to Estimate Genetic Variances?
Obtain estimates of genetic variances as an integral part of breeding program
# of variance components that can be estimated
= # of covariances among relatives in the design
However, estimate of additive genetic variance will be biased upward if there is GXE or epistasis
Not biased by GXE
Calculation of σA2 is the same as before
Are there significant differences among families?
F test MSF/MSFL= 14.36/6.18 = 2.32
Compare to Fcritical with 59,118 df
Pr>F is <0.0001
Bernardo, pg 155
Expected frequency of heterozygotes
P12 = 2pq(1-F)
Estimate additive genetic variance
= (14.36-6.18)/(2*3) = 1.36
appropriate error term for families
number of observations on each family
think of this as the square of the standard error of a family mean