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Consequences of paternally inherited effects on the genetic evaluation of maternal effects
BACKGROUND: Mixed models are commonly used for the estimation of variance components and genetic evaluation of livestock populations. Some evaluation models include two types of additive genetic effects, direct and maternal. Estimates of variance components obtained with models that account for mate...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2015
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4534045/ https://www.ncbi.nlm.nih.gov/pubmed/26268933 http://dx.doi.org/10.1186/s12711-015-0141-5 |
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author | Varona, Luis Munilla, Sebastián Casellas, Joaquim Moreno, Carlos Altarriba, Juan |
author_facet | Varona, Luis Munilla, Sebastián Casellas, Joaquim Moreno, Carlos Altarriba, Juan |
author_sort | Varona, Luis |
collection | PubMed |
description | BACKGROUND: Mixed models are commonly used for the estimation of variance components and genetic evaluation of livestock populations. Some evaluation models include two types of additive genetic effects, direct and maternal. Estimates of variance components obtained with models that account for maternal effects have been the subject of a long-standing controversy about strong negative estimates of the covariance between direct and maternal effects. Genomic imprinting is known to be in some cases statistically confounded with maternal effects. In this study, we analysed the consequences of ignoring paternally inherited effects on the partitioning of genetic variance. RESULTS: We showed that the existence of paternal parent-of-origin effects can bias the estimation of variance components when maternal effects are included in the evaluation model. Specifically, we demonstrated that adding a constraint on the genetic parameters of a maternal model resulted in correlations between relatives that were the same as those obtained with a model that fits only paternally inherited effects for most pairs of individuals, as in livestock pedigrees. The main consequence is an upward bias in the estimates of the direct and maternal additive genetic variances and a downward bias in the direct-maternal genetic covariance. This was confirmed by a simulation study that investigated five scenarios, with the trait affected by (1) only additive genetic effects, (2) only paternally inherited effects, (3) additive genetic and paternally inherited effects, (4) direct and maternal additive genetic effects and (5) direct and maternal additive genetic plus paternally inherited effects. For each scenario, the existence of a paternally inherited effect not accounted for by the estimation model resulted in a partitioning of the genetic variance according to the predicted pattern. In addition, a model comparison test confirmed that direct and maternal additive models and paternally inherited models provided an equivalent fit. CONCLUSIONS: Ignoring paternally inherited effects in the maternal models for genetic evaluation can lead to a specific pattern of bias in variance component estimates, which may account for the unexpectedly strong negative direct-maternal genetic correlations that are typically reported in the literature. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12711-015-0141-5) contains supplementary material, which is available to authorized users. |
format | Online Article Text |
id | pubmed-4534045 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2015 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-45340452015-08-13 Consequences of paternally inherited effects on the genetic evaluation of maternal effects Varona, Luis Munilla, Sebastián Casellas, Joaquim Moreno, Carlos Altarriba, Juan Genet Sel Evol Research Article BACKGROUND: Mixed models are commonly used for the estimation of variance components and genetic evaluation of livestock populations. Some evaluation models include two types of additive genetic effects, direct and maternal. Estimates of variance components obtained with models that account for maternal effects have been the subject of a long-standing controversy about strong negative estimates of the covariance between direct and maternal effects. Genomic imprinting is known to be in some cases statistically confounded with maternal effects. In this study, we analysed the consequences of ignoring paternally inherited effects on the partitioning of genetic variance. RESULTS: We showed that the existence of paternal parent-of-origin effects can bias the estimation of variance components when maternal effects are included in the evaluation model. Specifically, we demonstrated that adding a constraint on the genetic parameters of a maternal model resulted in correlations between relatives that were the same as those obtained with a model that fits only paternally inherited effects for most pairs of individuals, as in livestock pedigrees. The main consequence is an upward bias in the estimates of the direct and maternal additive genetic variances and a downward bias in the direct-maternal genetic covariance. This was confirmed by a simulation study that investigated five scenarios, with the trait affected by (1) only additive genetic effects, (2) only paternally inherited effects, (3) additive genetic and paternally inherited effects, (4) direct and maternal additive genetic effects and (5) direct and maternal additive genetic plus paternally inherited effects. For each scenario, the existence of a paternally inherited effect not accounted for by the estimation model resulted in a partitioning of the genetic variance according to the predicted pattern. In addition, a model comparison test confirmed that direct and maternal additive models and paternally inherited models provided an equivalent fit. CONCLUSIONS: Ignoring paternally inherited effects in the maternal models for genetic evaluation can lead to a specific pattern of bias in variance component estimates, which may account for the unexpectedly strong negative direct-maternal genetic correlations that are typically reported in the literature. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12711-015-0141-5) contains supplementary material, which is available to authorized users. BioMed Central 2015-08-13 /pmc/articles/PMC4534045/ /pubmed/26268933 http://dx.doi.org/10.1186/s12711-015-0141-5 Text en © Varona et al. 2015 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. |
spellingShingle | Research Article Varona, Luis Munilla, Sebastián Casellas, Joaquim Moreno, Carlos Altarriba, Juan Consequences of paternally inherited effects on the genetic evaluation of maternal effects |
title | Consequences of paternally inherited effects on the genetic evaluation of maternal effects |
title_full | Consequences of paternally inherited effects on the genetic evaluation of maternal effects |
title_fullStr | Consequences of paternally inherited effects on the genetic evaluation of maternal effects |
title_full_unstemmed | Consequences of paternally inherited effects on the genetic evaluation of maternal effects |
title_short | Consequences of paternally inherited effects on the genetic evaluation of maternal effects |
title_sort | consequences of paternally inherited effects on the genetic evaluation of maternal effects |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4534045/ https://www.ncbi.nlm.nih.gov/pubmed/26268933 http://dx.doi.org/10.1186/s12711-015-0141-5 |
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