Genet. Sel. Evol.
Volume 33, Number 4, July-August 2001
|Page(s)||369 - 395|
Genet. Sel. Evol. 33 (2001) 369-395
Simulation analysis to test the influence of model adequacy and data structure on the estimation of genetic parameters for traits with direct and maternal effectsVirginie Clémenta, Bernard Bibéa, Étienne Verrierb, c, Jean-Michel Elsena, Eduardo Manfredia, Jacques Bouixa and Éric Hanocqa
a Station d'amélioration génétique des animaux, Institut national de la recherche agronomique, BP 27, 31326 Castanet-Tolosan Cedex, France
b Station de génétique quantitative et appliquée, Institut national de la recherche agronomique, 78352 Jouy-en-Josas Cedex, France
c Département des sciences animales, Institut national agronomique Paris-Grignon, 16 rue Claude Bernard, 75231 Paris Cedex 05, France
(Received 3 May 2000; accepted 5 May 2001)
Simulations were used to study the influence of model adequacy and data structure on the estimation of genetic parameters for traits governed by direct and maternal effects. To test model adequacy, several data sets were simulated according to different underlying genetic assumptions and analysed by comparing the correct and incorrect models. Results showed that omission of one of the random effects leads to an incorrect decomposition of the other components. If maternal genetic effects exist but are neglected, direct heritability is overestimated, and sometimes more than double. The bias depends on the value of the genetic correlation between direct and maternal effects. To study the influence of data structure on the estimation of genetic parameters, several populations were simulated, with different degrees of known paternity and different levels of genetic connectedness between flocks. Results showed that the lack of connectedness affects estimates when flocks have different genetic means because no distinction can be made between genetic and environmental differences between flocks. In this case, direct and maternal heritabilities are under-estimated, whereas maternal environmental effects are overestimated. The insufficiency of pedigree leads to biased estimates of genetic parameters.
Key words: genetic parameters / animal model / maternal effects / simulations / connectedness
Correspondence and reprints: Virginie Clément
© INRA, EDP Sciences 2001