Coheritability and Coenvironmentability as Concepts for Partitioning the Phenotypic Correlation

Abstract

Central to the study of joint inheritance of quantitative traits is the determination of the degree of association between two phenotypic characters, and to quantify the relative contribution of shared genetic and environmental components influencing such relationship. One way to approach this problem builds on classical quantitative genetics theory, where the phenotypic correlation [Formula] between two traits is modelled as the sum of a genetic component called the coheritability (hx,y), which reflects the degree of shared genetics influencing the phenotypic correlation, and an environmental component, namely the coenvironmentability (ex,y) that accounts for all other factors that exert influence on the observed trait-trait association. Here a mathematical and statistical framework is presented on the partition of the phenotypic correlation into these components. I describe visualization tools to analyze [Formula] and ex,y concurrently, in the form of a three-dimensional (3DHER-plane) and a two-dimensional (2DHER-field) plots. A large data set of genetic parameter estimates (heritabilities, genetic and phenotypic correlations) was compiled from an extensive literature review, from which coheritability and coenvironmentability were derived, with the object to observe patterns of distribution, and tendency. Illustrative examples from a diverse set of published studies show the value of applying this partition to generate hypotheses proposing the differential contribution of shared genetics and shared environment to an observed phenotypic relationship between traits.