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 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 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.

Coheritability and Genetic Advances of Agromorphological and Oil Quality Traits in Groundnut (Arachis hypogaea L.) Genotypes from Ethiopia

“…Despite the various terms and methods used for measuring it [14], the coheritability estimate is being one of the basic parameters for measuring the coinheritance of traits [15]. e advantage of this genetic parameter over the genetic correlation coefficient is quite obvious as the latter throws light only on the magnitude of relationship among traits in the existing generation and not their coinheritance [16,17].…”

Genetic association of agronomic traits with partial resistance to gray leaf spot in elite maize germplasm

“…Standard errors of genotypic correlations and approximate 95% CI were calculated as described above. Coheritability $$({C}_{{h}_{xy}})$$ between trait pairs were computed from phenotypic and genotypic variances as described by Vasquez‐Kool (2019). Similarly, SE of and coheritability estimates were calculated as described by Vasquez‐Kool (2019) and estimates of coheritability were declared significant as described above.…”

“…However, pleiotropy may be absent if traits are influenced to a similar extent by environmental conditions manifested as nonheritable correlation. This phenomenon, referred to as environmental correlation, directly contributes to deviation of phenotypic or genotypic correlation from coheritability due to the confounding effects of the environment (Holland, 2006; Vasquez‐Kool, 2019). Since coheritability depicts the concurrent or recursive inheritance of traits, it reflects the effectiveness of tandem selection and facilitates the development of appropriate methods to incorporate multiple desirable traits into new germplasm.…”

Knowledge-driven approaches to improve genomic prediction in plants

“…The relationship between PLA and photosynthesis parameters was studied in terms of their phenotypic correlation (rP). The phenotypic correlation between two traits x and y can be defined as the sum of their coheritability (cx,y) and coenvironmentability (ex,y), where rPx,y, cx,y and ex,y ∈ [−1, 1], with the constraint that �𝑐𝑐 �,� � + �𝑒𝑒 �,� � � 1 (NEI 1960, Vasquez-Kool 2019:…”

“…However, a larger genetic correlation may not translate into a larger shared genetic component if heritabilities are small. To this end, Vasquez-Kool (2019) proposed to weigh genetic correlations by the geometric mean of heritabilities, called coheritability (c).…”