THE EFFECTS OF POPULATION SIZE AND DOMINANCE OF QUANTITATIVE TRAIT LOCI (QTL) ON THE DETECTION OF LINKAGE BETWEEN MARKERS AND QTL FOR LIVESTOCK

A simulation study on detection of linkage between genetic markers and QTL in backcross design was conducted. The effects of various sample sizes and the degree of QTL dominance on detention of linkage were examined by using a simple regression analysis. The results indicated that as sample size increased, the standard error of the estimated slope became smaller. When the dominance effect of QTL was complete, the estimated slope tended to be negative but was statistically not significant at all with type I error of greater than 50%. With complete linkage between genetic Marker and QTL, the estimated intercept value was smallest but the estimated slope was largest as expected. In most cases with various degree of dominance and sample sizes, when the actual recombination rate became larger, greater values were obtained for the slope except in the case of complete dominance of QTL.