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dc.contributor.authorde Villemereuil, P.
dc.contributor.authorMorrissey, M. B.
dc.contributor.authorNakagawa, S.
dc.contributor.authorSchielzeth, H.
dc.identifier.citationde Villemereuil , P , Morrissey , M B , Nakagawa , S & Schielzeth , H 2018 , ' Fixed-effect variance and the estimation of repeatabilities and heritabilities : issues and solutions ' , Journal of Evolutionary Biology , vol. 31 , no. 4 , pp. 621-632 .
dc.identifier.otherPURE: 252336874
dc.identifier.otherPURE UUID: 8b4d040c-af90-4a32-b19c-2bb945ddb4d0
dc.identifier.otherBibtex: urn:473054b2d80c71c8e5414e824d70afa1
dc.identifier.otherScopus: 85042129142
dc.identifier.otherWOS: 000429001800012
dc.descriptionHS was supported by an Emmy Noether fellowship from the German Research Foundation (DFG; SCHI 1188/1-1). SN is supported by a Future Fellowship, Australia (FT130100268). MBM is supported by a University Research Fellowship from the Royal Society (London).en
dc.description.abstractLinear mixed-effects models are frequently used for estimating quantitative genetic parameters, including the heritability, as well as the repeatability, of traits. Heritability acts as a filter that determines how efficiently phenotypic selection translates into evolutionary change, whereas repeatability informs us about the individual consistency of phenotypic traits. As quantities of biological interest, it is important that the denominator, the phenotypic variance in both cases, reflects the amount of phenotypic variance in the relevant ecological setting. The current practice of quantifying heritabilities and repeatabilities from mixed-effects models frequently deprives their denominator of variance explained by fixed effects (often leading to upward bias of heritabilities and repeatabilities), and it has been suggested to omit fixed effects when estimating heritabilities in particular. We advocate an alternative option of fitting models incorporating all relevant effects, while including the variance explained by fixed effects into the estimation of the phenotypic variance. The approach is easily implemented and allows optimizing the estimation of phenotypic variance, for example by the exclusion of variance arising from experimental design effects while still including all biologically relevant sources of variation. We address the estimation and interpretation of heritabilities in situations in which potential covariates are themselves heritable traits of the organism. Furthermore, we discuss complications that arise in generalized and nonlinear mixed models with fixed effects. In these cases, the variance parameters on the data scale depend on the location of the intercept and hence on the scaling of the fixed effects. Integration over the biologically relevant range of fixed effects offers a preferred solution in those situations.
dc.relation.ispartofJournal of Evolutionary Biologyen
dc.rights© 2018 European Society For Evolutionary Biology. Journal of Evolutionary Biology. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at
dc.subjectFixed effectsen
dc.subjectGeneralised linear mixed modellingen
dc.subjectVariance component analysisen
dc.subjectQuantitative geneticsen
dc.subjectQH301 Biologyen
dc.subjectQH426 Geneticsen
dc.titleFixed-effect variance and the estimation of repeatabilities and heritabilities : issues and solutionsen
dc.typeJournal articleen
dc.contributor.institutionUniversity of St Andrews.School of Biologyen
dc.contributor.institutionUniversity of St Andrews.Centre for Biological Diversityen
dc.description.statusPeer revieweden

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