Estimating heritability and genetic correlation between traits from generations F2 and F 3 of self-fertilizing species: a comparison of three methods.

Three methods of estimation of heritability and genetic correlation between traits in the F2 and F3 generations of self-fertilizing species were compared. The methods were: 1. Subtracting the estimates of environmental variances and covariances from the corresponding phenotypic estimates in the segregating generation which yields 'broad-sense' heritability and genetic correlation. 2. Analyses of variance and covariance of full-sib families; correlations were calculated from the between-families components and heritability was estimated by using intraclass correlation. 3. Offspring on parent regression for single traits and pairs of traits which yields estimates of heritability and genetic correlation. Theoretically, the family-analysis method is superior to the two others, because those estimates are less affected by non-additive genetic variance and covariance. Actual estimates for six traits in peanuts and their 15 two-trait combinations were calculated only for the purpose of comparison between the three methods. These estimates seem to be in agreement with conclusions which were drawn from the theoretical considerations.