Design and Efficiency of Selection Experiments for Estimating Genetic Parameters

Abstract

(i) Formulae are derived for the sampling variance of selection response and for estimates of realised heritability and realised genetic correlation. (ii) If a control population is maintained, or divergent selection practised, the greater part of the sampling variance comes from genetic drift and depends primarily on the total number of individuals recorded in the whole experiment, rather than on its duration. (iii) The optimal selection intensity for estimating realised heritabilities is investigated-proportions selected of about 15 per cent should be satisfactory. Similar designs will also be efficient for estimation of realised genetic correlations. (iv) Several methods of estimating heritability are compared, of these the realised heritability has least variance. (v) Some selection indices for improving a single trait are evaluated. Mass selection is likely to be best for comparing response from alternative selection programmes or populations.