Issue |
Genet. Sel. Evol.
Volume 34, Number 2, March-April 2002
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Page(s) | 171 - 192 | |
DOI | https://doi.org/10.1051/gse:2002002 |
Genet. Sel. Evol. 34 (2002) 171-192
DOI: 10.1051/gse:2002002
Optimal selection on two quantitative trait loci with linkage
Jack C.M. Dekkersa, Reena Chakrabortya and Laurence Moreauba Department of Animal Science, 225 Kildee Hall, Iowa State University Ames, IA, 50011, USA
b Inra-UPS-Ina PG, Station de génétique végétale, Ferme du Moulon, 91190 Gif-sur-Yvette, France
(Received 5 February 2001; accepted 15 October 2001)
Abstract
A mathematical approach to optimize selection on multiple quantitative
trait loci (QTL) and an estimate of residual polygenic effects was
applied to selection on two linked or unlinked additive
QTL. Strategies to maximize total or cumulative discounted response
over ten generations were compared to standard QTL selection on the
sum of breeding values for the QTL and an estimated breeding value for
polygenes, and to phenotypic selection. Optimal selection resulted in
greater response to selection than standard QTL or phenotypic
selection. Tight linkage between the QTL (recombination rate 0.05)
resulted in a slightly lower response for standard QTL and phenotypic
selection but in a greater response for optimal selection. Optimal
selection capitalized on linkage by emphasizing selection on favorable
haplotypes. When the objective was to maximize total response after
ten generations and QTL were unlinked, optimal selection increased QTL
frequencies to fixation in a near linear manner. When starting
frequencies were equal for the two QTL, equal emphasis was given to
each QTL, regardless of the difference in effects of the QTL and
regardless of the linkage, but the emphasis given to each of the two
QTL was not additive. These results demonstrate the ability of optimal
selection to capitalize on information on the complex genetic basis of
quantitative traits that is forthcoming.
Key words: selection / marker-assisted selection / quantitative trait loci / optimization
Correspondence and reprints: Jack C.M. Dekkers
e-mail: jdekkers@iastate.edu
© INRA, EDP Sciences 2002