QTL Mapping: Overview and Using Inbred Lines

While the machinery of quantitative genetics can blissfully function in complete ignorance of any of the underlying genetic details, we are certainly interested (at least one some level) on the genetic basis of trait variation. At the most practical level, if a gene of major effect is segregating in our population of interest, we would certainly like to not only to be aware of this, but also to fine map it for future exploration/exploitation. Often no single locus contributes more than a small fraction of the total genetic variation in a trait. In such cases, we often use the term polygene for one of these loci of small effect. The (still evolving) more modern use is to call these genes quantitative trait loci, or simply QTL or QTLs for short.