tailieunhanh - Báo cáo sinh học: "Detection of cytoplasmic effects on production: the influence of number of years of data"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Detection of cytoplasmic effects on production:the influence of number of years of data | Genet Sei Evol 1997 29 269-277 Elsevier Inra 269 Original article Detection of cytoplasmic effects . _ production the influence of number of years of data A Salehi JW James Department of Wool and Animal Science The University of New South Wales Sydney 2052 Australia Received 17 January 1995 revised 6 January 1997 accepted 3 March 1997 Summary - Data were simulated for a single trait determined by additive genetic cytoplasmic and environmental effects in a sheep flock. The proportions of variance due to genotype and cytoplasm were h2 or and c2 or with an extra set in which h2 and c2 0. For all five parameter sets two periods 10 or 20 years were considered with the same number of records in each case. Ten replicates of each were run so that 100 independent data sets were obtained. A ten-year data set with half the number of animals was also run giving 150 analyses in all. Data sets were analysed by derivative-free restricted maximum likelihood fitting four models which included additive genotype alone or in combination with either or both an additive genetic maternal effect and a cytoplasmic effect. If the cytoplasmic effect were omitted from the analysis model heritability and maternal variance were overestimated. If cytoplasmic effects were included parameter estimates were close to true values. Heritability did not affect the power of tests for cytoplasmic effects which was higher for c2 than for c2 . Detection of cytoplasmic variance was more likely with data spread over 20 rather than over 10 years and power was reduced with fewer data. cytoplasmic effect restricted maximum likelihood animal model sheep Resume Detection d effets cytoplasmiques sur des caractères de production incidence du nombre des années avec données. On a simulé des données pour un carac-tère determine par les effets génétiques additifs cytoplasmiques et de milieu dans un troupeau de moutons. Les parts de variance phénotypique dues aux effets génétiques et .