Heritability at family mean level

Viana, José Marcelo Soriano

doi:10.1590/s0100-67622002000300002

Cited by 4 publications

(7 citation statements)

References 3 publications

(3 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This correlation is equal to the square root of the narrow-sense heritability at the individual level (Viana, 2002). If the selection units are half sib families, the efficiency of among-family selection is proportional to the correlation between the mean phenotypic value of the progeny and the additive genetic value of the common parent, that is equal to the square root of the narrow-sense heritability at the family level (Viana, 2002), because the correlation between the number of genes that increase the trait expression in the common parent (N) and the mean frequency of these genes in the family (p) is: 70 Viana Table 1 -Correlations between the number of genes that increase the trait expression (N) and the additive genetic value (A) and the genotypic value (G; assuming absence of epistasis), considering three genes, different populations (p is the frequency of the dominant gene) and four degrees of dominance. …”

Section: Genotypic Variance In Non-inbred Populationsmentioning

confidence: 99%

“…When the selection units are full sib families, the efficiency of among-family selection is proportional to the correlation between the mean phenotypic value of the progeny and the mean of the additive genetic values of the parents, that is equal to the square root of the narrow-sense heritability at the family level (Viana, 2002), because the correlation between the mean number of genes that increases the trait expression (N) and the mean frequency of these genes in the family (p) is:…”

Section: Genotypic Variance In Non-inbred Populationsmentioning

confidence: 99%

“…In many situations, depending on the selection unit and on the experimental data, it is only possible to assess the efficiency of a selective process from the broad-sense heritability, which is equal to the square of the correlation between the phenotypic and genotypic values of the selection unit (Viana, 2002). In these cases, as this heritability is greater than the corresponding narrow-sense heritability, the efficiency of selection is in general overestimated because of the lower value of the correlation between the genotypic value of the individual and the number of favorable genes present.…”

Section: Genotypic Variance In Non-inbred Populationsmentioning

confidence: 99%

See 2 more Smart Citations

Dominance, epistasis, heritabilities and expected genetic gains

Viana

2005

Genet. Mol. Biol.

Self Cite

View full text Add to dashboard Cite

Although epistasis is common in gene systems that determine quantitative traits, it is usually not possible to estimate the epistatic components of genotypic variance because experiments in breeding programs include only one type of progeny. As the study of this phenomenon is complex, there is a lack of theoretical knowledge on the contribution of the epistatic variances when predicting gains from selection and on the bias in estimating genetic parameters when fitting the additive-dominant model. The objective of this paper is to discuss these aspects. Regarding a non-inbred population, the genetic value due to dominance and the epistatic components of the genotypic value are not indicators of the number of favorable genes present in an individual. Thus, the efficiency of a selection process should be based on the narrow-sense heritability, a function only of additive variance. If there is no epistasis, generally it is satisfactory to assess the selection efficiency and to predict gain based on the broad-sense heritability. Regardless of the selection unit or type of epistasis, the bias in the estimate of the additive variance when assuming the additive-dominant model is considerable. This implies overestimation of the heritabilities at half sib family mean, plant within family and plant levels, and underestimation if the selection units are full sib progenies. The predicted gains will have a bias proportional to that of the heritability.

show abstract

Section: Genotypic Variance In Non-inbred Populationsmentioning

confidence: 99%

Section: Genotypic Variance In Non-inbred Populationsmentioning

confidence: 99%

Section: Genotypic Variance In Non-inbred Populationsmentioning

confidence: 99%

See 1 more Smart Citation

Dominance, epistasis, heritabilities and expected genetic gains

Viana

2005

Genet. Mol. Biol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The narrow sense heritability at individual level in the generation 0 is the square of the correlation between the phenotypic and additive genetic values (Falconer and MacKay, 1996;Viana, 2002), given by …”

Section: Heritabilities and Genetic Gainsmentioning

confidence: 99%

“…The narrow sense heritability at half-sib family mean level is the square of the correlation between the mean phenotypic value of the progeny and the additive genetic value of the common parent (Viana, 2002), given by Linkage disequilibrium is, then, cause of bias only in predicting gain from within selection.…”

Section: = σ σmentioning

confidence: 99%

Quantitative genetics theory for non-inbred populations in linkage disequilibrium

Viana

2004

Genet. Mol. Biol.

Self Cite

View full text Add to dashboard Cite

Although linkage disequilibrium, epistasis and inbreeding are common phenomena in genetic systems that control quantitative traits, theory development and analysis are very complex, especially when they are considered together. The objective of this study is to offer additional quantitative genetics theory to define and analyze, in relation to non-inbred cross-pollinating populations, components of genotypic variance, heritabilities and predicted gains, assuming linkage disequilibrium and absence of epistasis. The genotypic variance and its components, additive and due to dominance genetic variances, are invariant over the generations only in regard to completely linked genes and to those in equilibrium. When the population is structured in half-sib families, the additive variance in the parents' generation and the genotypic variance in the population can be estimated. When the population is structured in full-sib families, none of the components of genotypic variance can be estimated. The narrow sense heritability at plant level can be estimated from the parent-offspring or mid parent-offspring regression. When there is dominance, the narrow sense heritability estimate in the in F 2 is biased due to linkage disequilibrium when estimated by the Warner method, but not when estimated by means of the plant F 2 -family F 3 regression. The bias is proportional to the number of pairs of linked genes, without independent assortment, and to the degree of dominance, and tends to be positive when genes in the coupling phase predominate or negative and of higher value when genes in the repulsion phase predominate. Linkage disequilibrium is also cause of bias in estimates of the narrow sense heritabilities at full-sib family mean and at plant within half-sib and full-sib families levels. Generally, the magnitude of the bias is proportional to the number of pairs of genes in disequilibrium and to the frequency of recombining gametes.

show abstract

Estimating heritability using family-pooled phenotypic and genotypic data: a simulation study applied to aquaculture

et al. 2022

View full text Add to dashboard Cite

Estimating heritability based on individual phenotypic and genotypic measurements can be expensive and labour-intensive in commercial aquaculture breeding. Here, the feasibility of estimating heritability using within-family means of phenotypes and allelic frequencies was investigated. Different numbers of full-sib families and family sizes across ten generations with phenotypic and genotypic information on 10 K SNPs were analysed in ten replicates. Three scenarios, representing differing numbers of pools per family (one, two and five) were considered. The results showed that using one pool per family did not reliably estimate the heritability of family means. Using simulation parameters appropriate for aquaculture, at least 200 families of 60 progeny per family divided equally in two pools per family was required to estimate the heritability of family means effectively. Although application of five pools generated more within- and between- family relationships, it reduced the number of individuals per pool and increased within-family residual variation, hence, decreased the heritability of family means. Moreover, increasing the size of pools resulted in increasing the heritability of family means towards one. In addition, heritability of family mean estimates were higher than family heritabilities obtained from Falconer’s formula due to lower intraclass correlation estimate compared to the coefficient of relationship.

show abstract

Heritability at family mean level

Cited by 4 publications

References 3 publications

Dominance, epistasis, heritabilities and expected genetic gains

Dominance, epistasis, heritabilities and expected genetic gains

Quantitative genetics theory for non-inbred populations in linkage disequilibrium

Estimating heritability using family-pooled phenotypic and genotypic data: a simulation study applied to aquaculture

Contact Info

Product

Resources

About