It is a section of DNA (the locus) that correlates with variation in a phenotype (the quantitative trait).
Files that contain the .qtl file extension are text files that store QuickTime movie file links. These QTL files include the location of the associated movie file and the file's QuickTime settings. Some of the settings within the QTL file may include autoplay settings, controller settings, loop settings, etc. When you click a QTL link, it will open the associated movie file within the QuickTime media player as long as the Web server is configured with the proper MIME type. The movie files that a QTL file references are located on a Web server and the files allow a user to download or stream the associated movie to his or her hard drive. Quantitative trait locus (QTL) analysis is a statistical method that links two types of information—phenotypic data (trait measurements) and genotypic data (usually molecular markers)—in an attempt to explain the genetic basis of variation in complex traits (Falconer & Mackay, 1996; Kearsey, 1998; Lynch & Walsh, 1998). A meta-analysis of extensive data in pigs and dairy found that QTL effects were skewed towards fewer QTL with large effects (Hayes and Goddard 2001). Orr (2001) addresses the question of defining and distinguishing between large and small effects. As with all statistical analyses, sample size is a critical factor. A principal goal of QTL analysis has been to answer the question of whether phenotypic differences are primarily due to a few loci with fairly large effects, or to many loci, each with minute effects. A meta-analysis of extensive data in pigs and dairy found that QTL effects were skewed towards fewer QTL with large effects (Hayes and Goddard 2001). Orr (2001) addresses the question of defining and distinguishing between large and small effects. As with all statistical analyses, sample size is a critical factor. Because the logical next step, after identifying a QTL, is to figure out what it is about that region which influences the measured trait. If the QTL in question is too large, that could mean trying to take a list of dozens or hundreds of genes and, somehow, devising a test to prove: It’s this one! Gene AT1G15210 helps regulate height (or root hairs, or trichomes, or whatever it is being studied). If the average height of all the individuals with version A of some part of the genome is higher than the average height for all individuals which have version B of that same part of the genome and that difference is significant after a whole bunch of statistical tests, then that region is a QTL. A quantitative trait locus (QTL) is a section of DNA (the locus) that correlates with variation in a phenotype (the quantitative trait). The QTL typically is linked to, or contains, the genes that control that phenotype. The simplest method for QTL mapping is analysis of variance (ANOVA, sometimes called marker regression) at the marker loci. In this method, in a backcross, one may calculate a t-statistic to compare the averages of the two marker genotype groups. a) Quantitative trait locus (QTL) mapping requires parental strains (red and blue plots) that differ genetically for the trait, such as lines created by divergent artificial selection. A meta-analysis of extensive data in pigs and dairy found that QTL effects were skewed towards fewer QTL with large effects (Hayes and Goddard 2001). Orr (2001) addresses the question of defining and distinguishing between large and small effects. As with all statistical analyses, sample size is a critical factor. It is also possible to perform QTL analysis on unmanipulated natural populations using hybrids, sibships (half-sibling or full-sibling families), and/or pedigree information (Lynch & Walsh, 1998; Mott et al. , 2000; Slate, 2005). A meta-analysis of extensive data in pigs and dairy found that QTL effects were skewed towards fewer QTL with large effects (Hayes and Goddard 2001). Orr (2001) addresses the question of defining and distinguishing between large and small effects. As with all statistical analyses, sample size is a critical factor. QTL mapping/interval mapping-for quantitative traits like height that are polygenic. Same as linkage mapping except the phenotype is continuous and the markers are put into a scoring scheme to measure their contribution-i.e. marker effects or allelic contribution. Big in agriculture.  A quantitative trait locus (QTL) is a region of DNA that is associated with a particular phenotypic trait. These QTLs are often found on different chromosomes. Knowing the number of QTLs that explains variation in the phenotypic trait tells us about the genetic architecture of a trait. The simplest method for QTL mapping is analysis of variance (ANOVA, sometimes called marker regression) at the marker loci. In this method, in a backcross, one may calculate a t-statistic to compare the averages of the two marker genotype groups.
http://file.org/extension/qtl http://www.nature.com/scitable/topicpage/Quantitative-Trait-Locus-QTL-Analysis-53904 http://www.nature.com/scitable/topicpage/Quantitative-Trait-Locus-QTL-Analysis-53904 http://www.jamesandthegiantcorn.com/2011/10/06/what-is-a-qtl/ https://en.wikipedia.org/wiki/Quantitative_trait_locus http://www.nature.com/scitable/topicpage/Quantitative-Trait-Locus-QTL-Analysis-53904 http://www.nature.com/scitable/topicpage/Quantitative-Trait-Locus-QTL-Analysis-53904 https://www.biostars.org/p/47725/ https://en.wikipedia.org/wiki/Quantitative_trait_locus
what is a QTL