tailieunhanh - Báo cáo sinh học: "A comparison of bivariate and univariate QTL mapping in livestock populations"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học thế giới đề tài: A comparison of bivariate and univariate QTL mapping in livestock populations | 605 Genet Sei. Evol. 35 2003 605-622 INRA EDP Sciences 2003 DOI gse 2003042 Original article a comparison of bivariate and univariate QTL mapping in livestock populations Peter Sorensen Mogens Sand0 Lund Bernt Guldbrandtsen Just Jensen Daniel Sorensen Danish Institute of Agricultural Sciences Department of Animal Breeding and Genetics Research Centre Foulum PO Box 50 8830 Tjele Denmark Received 22 April 2002 accepted 6 March 2003 Abstract - This study presents a multivariate variance component-based QTL mapping model implemented via restricted maximum likelihood REML . The method was applied to investigate bivariate and univariate QTL mapping analyses using simulated data. Specifically we report results on the statistical power to detect a QTL and on the precision of parameter estimates using univariate and bivariate approaches. The model and methodology were also applied to study the effectiveness of partitioning the overall genetic correlation between two traits into a component due to many genes of small effect and one due to the QTL. It is shown that when the QTL has a pleiotropic effect on two traits a bivariate analysis leads to a higher statistical power of detecting the QTL and to a more precise estimate of the QTL s map position in particular in the case when the QTL has a small effect on the trait. The increase in power is most marked in cases where the contributions of the QTL and of the polygenic components to the genetic correlation have opposite signs. The bivariate REML analysis can successfully partition the two components contributing to the genetic correlation between traits. multivariate QTL mapping livestock 1. introduction In many quantitative trait loci QTL mapping experiments in livestock populations a number of phenotypic traits are recorded . 8 11 26 . Usually QTL are mapped for individual traits using single trait analyses. The traits however may be environmentally and genetically correlated. A genetic correlation can be the .