The expected distribution of marker-linked quantitative effects in crosses between inbred lines

The a priori theoretical distribution of marker-linked quantitative effects in crosses involving inbred lines, and the number of quantitative loci contributing to such effects was obtained by numerical analysis, and examined as a function of the number and effects of the quantitative loci differentiating the lines, the location of the marker relative to the chromosome ends, and the mapping function. Over a wide range of assumptions it was found that the probability that a given marker will have an associated linked quantitative effect equal in magnitude to 0.2 phenotypic standard deviations or greater is of the order of 0-10 or more. In most of these cases it can be expected that the marker-linked effects will be due to one, or at the most two, quantitative loci in the vicinity of the marker.