Markers which are close together on the chromosome will be less likely to undergo recombination. As such, close markers are said to be linked. By analyzing hundreds of markers, one can eventually build a genetic map. Mapping populations consist of a number of individuals at a stage in which alleles will be segregating in a Mendelian fashion. QTLs QTLs are segments of chromosomes found throughout the genome that contain one or many genes which drive the eventual expression of some quantitative trait.
Linkage affects the use of markers in breeding in two ways.
Without linkage disequilibrium, associations between markers and QTLs cannot be identified. DNA markers can be used to locate QTLs to a specific chromosomal location. They also are used to monitor the incorporation of the desirable alleles from the donor source. A brief overview of recent molecular breeding literature brings forth the names of researchers such as Tanksley, Stuber, and Edwards. Among the most prominent minds within the field of molecular breeding, these individuals paved the way for future molecular breeders.