Extent and consistency across generations of linkage disequilibrium in commercial layer chicken breeding populations.
Recent studies report a surprisingly high degree of marker-to-marker linkage disequilibrium (LD) in ruminant livestock populations. This has important implications for QTL mapping and marker-assisted selection. This study evaluated LD between microsatellite markers in a number of breeding populations of layer chickens using the standardized chi-square (chi(2')) measure. The results show appreciable LD among markers separated by up to 5 cM, decreasing rapidly with increased separation between markers. The LD within 5 cM was strongly conserved across generations and differed among chromosomal regions. Using marker-to-marker LD as an indication for marker-QTL LD, a genome scan of markers spaced 2 cM apart at moderate power would have good chances of uncovering most QTL segregating in these populations. However, of markers showing significant trait associations, only 57% are expected to be within 5 cM of the responsible QTL, and the remainder will be up to 20 cM away. Thus, high-resolution LD mapping of QTL will require dense marker genotyping across the region of interest to allow for interval mapping of the QTL.
Heifetz
E M
EM
Department of Genetics, Hebrew University, 91904 Jerusalem, Israel.
Fulton
J E
JE
O'Sullivan
N
N
Zhao
H
H
Dekkers
J C M
JC
Soller
M
M
D000818:Animals; D016009:Chi-Square Distribution; D002645:Chickens / Q000235:genetics*; D005819:Genetic Markers; D005828:Genetics, Population; D015810:Linkage Disequilibrium; D008297:Male; D011157:Population Dynamics; D040641:Quantitative Trait Loci; D026801:Synteny
D005819:Genetic Markers