Villanueva Beatriz, Avendaño Santiago, Woolliams John A
Scottish Agricultural College, West Mains Road, Edinburgh, EH9 3JG, Scotland, UK.
Genet Sel Evol. 2006 Mar-Apr;38(2):127-46. doi: 10.1186/1297-9686-38-2-127. Epub 2006 Feb 23.
There are selection methods available that allow the optimisation of genetic contributions of selection candidates for maximising the rate of genetic gain while restricting the rate of inbreeding. These methods imply selection on quadratic indices as the selection merit of a particular individual is a quadratic function of its estimated breeding value. This study provides deterministic predictions of genetic gain from selection on quadratic indices for a given set of resources (the number of candidates), heritability, and target rate of inbreeding. The rate of gain was obtained as a function of the accuracy of the Mendelian sampling term at the time of convergence of long-term contributions of selected candidates and the theoretical ideal rate of gain for a given rate of inbreeding after an exact allocation of long-term contributions to Mendelian sampling terms. The expected benefits from quadratic indices over traditional linear indices (i.e. truncation selection), both using BLUP breeding values, were quantified. The results clearly indicate higher gains from quadratic optimisation than from truncation selection. With constant rate of inbreeding and number of candidates, the benefits were generally largest for intermediate heritabilities but evident over the entire range. The advantage of quadratic indices was not highly sensitive to the rate of inbreeding for the constraints considered.
有一些可供选择的方法，这些方法能够在限制近交率的同时，通过优化选择候选个体的遗传贡献来最大化遗传进展速率。这些方法意味着基于二次指数进行选择，因为特定个体的选择价值是其估计育种值的二次函数。本研究针对给定的一组资源（候选个体数量）、遗传力和目标近交率，提供了基于二次指数选择的遗传进展的确定性预测。在选定候选个体的长期贡献收敛时，根据孟德尔抽样项的准确性以及在将长期贡献精确分配给孟德尔抽样项后给定近交率下的理论理想遗传进展速率，获得了遗传进展速率。对使用最佳线性无偏预测（BLUP）育种值的二次指数相对于传统线性指数（即截断选择）的预期益处进行了量化。结果清楚地表明，二次优化比截断选择能带来更高的遗传进展。在近交率和候选个体数量恒定的情况下，益处通常在中等遗传力时最大，但在整个范围内都很明显。对于所考虑的限制条件，二次指数的优势对近交率不太敏感。
