Déséquilibre de liaison et cartographie de QTL en population sélectionnée

Linkage disequilibrium (LD) is due to non random associations between alleles at two loci. It has become a classical tool to fine map loci implied in quantitative trait (Quantitative Trait Loci, QTL) determinism, through identification of the maxima of LD between alleles of a marker locus (or a group of marker loci) and a locus involved in the variability of a quantitative trait. The creation and intensity of LD evolves according to the evolutionary forces affecting the population. Among these forces, random drift and selection are particularly present in livestock populations. This PhD thesis aimed to study the influence of selection on the structure of LD around a QTL, as well as its impact on the precision on the fine mapping of QTL. A software has been developed to simulate the evolution of populations. Starting from a population in linkage equilibrium, LD due to evolutionary forces is created over historical generations. QTL detection is applied to the next generations where the pedigree is known. The main experimental designs applied in livestock populations are implemented in the software. All data used for the further analysis of this work were obtained from this simulation program. We first analyzed LD in the neighbourhood of the QTL by recording the location of the marker in maximum LD with the QTL. LD was estimated with two classical measures: D' and