Components of variation

Abstract

The last two chapters have shown the range of information that can be gained from comparisons among family means and the use to which these first degree statistics can be put in the genetical analysis of continuous variation. We must now turn to consider the constitution of the second degree statistics, the variances and covariances that can be calculated from the families raised in genetical experiments, and the information that they yield. In doing so it is convenient to proceed as we did with means and look first at the simple case in which dominance is taken into account but non-allelic interaction and genotype × environment interaction are neglected. The consequences of these interactions will be taken up in the next chapter, as will the effects of linkage.