Estimation of the true additive genetic variance sigma ki = 1 d2i in the presence of linkage disequilibrium.
Accurate estimates of the true additive genetic variance (sigma ki = 1 d2i) of a cross between two pure breeding varieties can be obtained from the additive genetic components of the first three ranks (D1, D2 and D3) when the latter are biased by the presence of linkage. Additive genetic variances of the lower ranks are directly equatable with sigma ki = 1 d2i because they incur minimal bias even when the predominating linkages are strong. More precise estimates of sigma ki = 1 d2i are however obtainable from the asymptotic regression analysis or a weighted least squares analysis. Estimates of sigma ki = 1 d2i when obtained from 784 hierarchically derived F7 families of the V2 X V12 cross of Nicotiana rustica were observed to be considerably larger than the additive genetic variance displayed by the F13 inbreds of the same cross for all the characters that showed significant excess of repulsion linkages. These results lend support to our commonly held view that the prediction procedures generally underestimate the probability of successful recovery of superior recombinant inbreds.
D000704:Analysis of Variance; D008040:Genetic Linkage; D014644:Genetic Variation; D007178:Inbreeding; D008957:Models, Genetic; D012044:Regression Analysis