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Báo cáo sinh học: " Equivalence of multibreed animal models and hierarchical Bayes analysis for maternally influenced traits"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học quốc tế đề tài: Equivalence of multibreed animal models and hierarchical Bayes analysis for maternally influenced traits | Munilla Leguizamón and Cantet Genetics Selection Evolution 2010 42 20 http www.gsejournal.Org content 42 1 20 GSE Ge n et i cs Selection Evolution RESEARCH Open Access Equivalence of multibreed animal models and hierarchical Bayes analysis for maternally influenced traits Sebastián Munilla Leguizamon1 2 Rodolfo JC Cantet1 2 Abstract Background It has been argued that multibreed animal models should include a heterogeneous covariance structure. However the estimation of the co variance components is not an easy task because these parameters can not be factored out from the inverse of the additive genetic covariance matrix. An alternative model based on the decomposition of the genetic covariance matrix by source of variability provides a much simpler formulation. In this study we formalize the equivalence between this alternative model and the one derived from the quantitative genetic theory. Further we extend the model to include maternal effects and in order to estimate the co variance components we describe a hierarchical Bayes implementation. Finally we implement the model to weaning weight data from an Angus X Hereford crossbred experiment. Methods Our argument is based on redefining the vectors of breeding values by breed origin such that they do not include individuals with null contributions. Next we define matrices that retrieve the null-row and the nullcolumn pattern and by means of appropriate algebraic operations we demonstrate the equivalence. The extension to include maternal effects and the estimation of the co variance components through the hierarchical Bayes analysis are then straightforward. A FORTRAN 90 Gibbs sampler was specifically programmed and executed to estimate the co variance components of the Angus X Hereford population. Results In general genetic co variance components showed marginal posterior densities with a high degree of symmetry except for the segregation components. Angus and Hereford breeds contributed with 50.26 and 41.73 of .