Computing Heritability and Selection Response From Unbalanced Plant Breeding Trials

TLDR

Heritability is used by plant breeders to gauge trial precision and predict response to selection, but standard formulas assume balanced data and independent genotypic effects, assumptions often violated in practice. This article proposes a simulation-based approach to address these limitations. The method directly simulates the quantity of interest, such as response to selection, instead of relying on ad hoc heritability approximations. The approach is demonstrated through three illustrative examples.

Abstract

Heritability is often used by plant breeders and geneticists as a measure of precision of a trial or a series of trials. Its main use is for computing the response to selection. Most formulas proposed for calculating heritability implicitly assume balanced data and independent genotypic effects. Both of these assumptions are often violated in plant breeding trials. This article proposes a simulation-based approach to tackle the problem. The key idea is to directly simulate the quantity of interest, e.g., response to selection, rather than trying to approximate it using some ad hoc measure of heritability. The approach is illustrated by three examples.