ABSTRACT
Quantitative trait loci (QTL) mapping experiments follow a common basic algorithm in many taxa. In experimental populations, one can virtually guarantee the detection of at least some QTLs by choosing parents which differ markedly for phenotypes of interest. Associations between allelic differences at a genetic marker locus and differences among individuals in phenotype, provide the basic evidence needed to identify and describe QTLs. Because “QTL mapping” involves extricating a genetic signal from many sources of “noise,” QTL locations and effects are typically described as “likelihood intervals,” chromosomal regions in which a QTL can be asserted to map with a specified level of statistical confidence. QTL mapping experiments are notorious for their unwieldy size. Most QTL experiments have involved more than 200 individuals, and in some cases as many as 2000 or more. An excellent approach for efficiently mapping QTLs which influence a single phenotype, is “selective genotyping.”
