the distribution of the effects of genes affecting quantitative traits in livestock的影响基因的分布影响的定量特征的牲畜.pdf

Genet. Sel. Evol. 33 (2001) 209–229 209 © INRA, EDP Sciences, 2001 Original article The distribution of the effects of genes affecting quantitative traits in livestock Ben HAYESa ,∗, Mike E. GODDARDa ,b a Institute of Land and Food Resources, University of Melbourne, Parkville, Victoria, 3052, Australia b Department of Natural Resources and Environment, Victorian Institute of Animal Science, Attwood, Victoria, 3049, Australia (Received 24 January 2000; accepted 2 January 2001) Abstract – Meta-analysis of information from quantitative trait loci (QTL) mapping experi- ments was used to derive distributions of the effects of genes affecting quantitative traits. The two limitations of such information, that QTL effects as reported include experimental error, and that mapping experiments can only detect QTL above a certain size, were accounted for. Data from pig and dairy mapping experiments were used. Gamma distributions of QTL effects were fitted with maximum likelihood. The derived distributions were moderately leptokurtic, consistent with many genes of small effect and few of large effect. Seventeen percent and 35% of the leading QTL explained 90% of the genetic variance for the dairy and pig distributions respectively. The number of segregating genes affecting a quantitative trait in dairy populations was predicted assuming genes affecting a quantitative trait were neutral with respect to fitness. Between 50 and 100 genes were predicted, depending on the effective population size assumed. As data for the analysis included no QTL of small effect, the ability to estimate the number of QTL of small effect must inevitably be weak. It may