Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh Original cung cấp cho các bạn kiến thức về sinh học đề tài:Phenotypic plasticity of body pigmentation in Drosophila: Inferences about variance components and selection response for body weight in chickens. | Genet Sei Evol 1997 29 413-425 Elsevier Inra 413 Original article Inferences about variance components and selection response for body weight in chickens G Su p S0rensen D Sorensen Department of Breeding and Genetics Danish Institute of Animal Science PO Box 39 8830 Tjele Denmark Received 6 January 1997 accepted 13 June 1997 Summary - Response to selection for body weight at 40 days was analyzed using least squares a REML BLUP approach and finally using Bayesian methods. The last two methods were implemented using an animal model that included a term accounting for a covariance among full-sibs effect other than the additive genetic. The data which originate from the Strynp breeding station in Denmark comprised 6 900 recorded individuals from 200 sires and 720 dams and covered eight generations of selection. The base population was formed from a population with a long history of selection for body weight. The least squares procedure yielded a total phenotypic change of g. The estimate of total genetic change based on REML BLUP was g and the Bayesian approach produced an estimate mean of the marginal posterior distribution ranging from to g depending on the prior distribution assumed for the variance components. This corresponds to a response per generation of about 45 g or of the mean of the base population. The Bayesian approach was implemented using the Gibbs sampler. The REML estimates of heritability and of the proportion of the variance due to the f effect were and respectively. The corresponding values obtained from the Bayesian analysis were approximately and regardless of the prior used. A likelihood ratio test indicated that the variance component due to the f effect should be included in the model. We speculate about the possible mechanisms that can lead to the f effect. selection daily gain in broilers Bayesian analysis Gibbs sampling Resume - Inferences concernant les composantes de la variance et la .
