Time trends of population means and heritability estimates of clutch traits in a white leghorn population subjected to long term selection

摘要

Time trends of population performances is a measure of direct or correlated phenotypic response. The magnitude of heritability in population provides a measure of additive genetic variability, which determines the potential for changing population means by selection. The additive genetic and phenotypic variances are reduced as a result of selection of parents. A group of selected parents represent one trait of the phenotypic distribution, and in consequence, their phenotypic variance must be less than that of the whole population from which they are selected (Bulmer, 1976, Falconer and Mackay, 1996).