A simple method to calculate resolving power and confidence interval of QTL map location

quantitative trait locus (QTL) map location that would be obtained when scoring an infinite number of markers in a given constellation of a marker- QTL mapping experiment. Resolving power can serve as a close estimate of the confidence interval of QTL map location, as well as a guide to the lower efficient limit of marker spacing in an initial marker-QTL mapping experiment. In the present study, an extensive series of simulations was carried out to provide estimates of resolving power, for backcross (BC) and F₂ designs. Over a wide range of experimental sizes and of gene effects and dominance at the QTL. From the simulation results, the remarkably simple expressions, 3000/(mNd²) (where m = 1 for BC and m = 2 for F₂; N = population size, and d = allele substitution effect) and 530/Nv (in terms of v, the proportion of variance explained), were obtained for estimating resolving power. These expressions can provide a convenient guide to planning marker spacing in BC and F₂ marker-QTL linkage experiments and for placing confidence intervals about QTL map location obtained in such experiments.