Why is usefulness rarely useful?

Abstract

Mate selection plays an important role in breeding programs. The usefulness criterion was proposed as a criterion for mate selection, combining information on both the mean and standard deviation of the potential offspring, particularly in clonally propagated outbred species where large family sizes are possible. Predicting mean values of offspring of a cross is generally easier than predicting the standard deviation, especially in outbred species where the linkage of alleles is often unknown and phasing is required. In this study, we developed a method for estimating phasing accuracy from unphased genotype data on possible parental lines and evaluated whether the accuracy was sufficient to predict family standard deviations of possible crosses using a set of simulations spanning a wide range of genetic architectures and genotypes from a real strawberry breeding population. We find that despite highly accurate computational phasing, predicting family standard deviations and using predicted values of the usefulness criterion per possible cross confers little benefit relative to simply selecting parents based on predicted family means. Therefore even in this species, which is clonally propagated, outbred, and produces large families, we find the usefulness criterion unlikely to be useful.