20 Correlated characters

20.1 Genetic and environmental correlations

20.1.1 Estimation of the genetic correlation

20.2 Correlated response to selection

20.2.1 Indirect selection

20.3 Genotype-environment interaction

20.4 Index selection

20.4.1 Construction of the index

20.4.2 Response

20.4.3 Effect of selection on genetic correlations