Tang G, Lin P, Xu C, Xue J, Liu T, Wang Z, Li X
College of Animal Science and Technology, Sichuan Agricultural University, Yaan 625014, China.
Livest Sci. 2011 Nov;141(2-3):242-251. doi: 10.1016/j.livsci.2011.06.010.
Two methods (Scheme A and Scheme B) were developed to optimize the relative weights on quantitative trait loci (QTL) and contributions of selected individuals simultaneously to maximize selection response while constraining the rate of inbreeding to the rate observed in gene assisted selection (GAS). In Scheme A, both the relative weights give to QTL and contributions of the selected individuals were optimized using a genetic algorithm. The possible solutions for relative weights of QTL and contributions of the selected individuals were encoded simultaneously. A physical selection population was used to evaluate the fitness of each encoded solution using stochastic simulation with 50 replicates. The fitness of each solution was the mean of all replicates for accumulative discounted sum of genetic means of all generations in physical selection population. In Scheme B, the optimization for relative weights on QTL was similar to Scheme A, and also was implemented based on a genetic algorithm. However, unlike Scheme A, an optimal contribution algorithm (OC) was used to optimize contributions of selection candidates. When compared with GAS, Schemes A and B resulted in up to 15.88 and 22.26% extra discounted sum of genetic value of all generations in a long planning horizon, respectively. Compared GAS+OC and Scheme B, most of the increase (about 78%) in genetic gain was produced by only optimizing contributions of selected individuals. The optimization for relative weight given to QTL just avoided the long-term loss (about 22%) observed in GAS scheme.
开发了两种方法(方案A和方案B)来同时优化数量性状位点(QTL)的相对权重和所选个体的贡献,以在将近亲繁殖率限制在基因辅助选择(GAS)中观察到的速率的同时最大化选择反应。在方案A中,使用遗传算法对赋予QTL的相对权重和所选个体的贡献进行优化。QTL的相对权重和所选个体的贡献的可能解决方案被同时编码。使用一个实际选择群体,通过50次重复的随机模拟来评估每个编码解决方案的适应性。每个解决方案的适应性是实际选择群体中所有世代遗传均值的累积折扣总和在所有重复中的平均值。在方案B中,对QTL相对权重的优化与方案A类似,也是基于遗传算法实施的。然而,与方案A不同的是,使用最优贡献算法(OC)来优化选择候选个体的贡献。与GAS相比,在长期规划中,方案A和方案B分别导致所有世代遗传价值的额外折扣总和增加了15.88%和22.26%。将GAS+OC和方案B进行比较,遗传增益的大部分增加(约78%)仅通过优化所选个体的贡献产生。对赋予QTL的相对权重进行优化只是避免了在GAS方案中观察到的长期损失(约22%)。