长期选择与群体某些参数的变化趋势初探

采用理论模拟与实地选种资料分析对比的方法,对长期选择作用下的群体变化特征作了初步探讨。实地选种资料取自南斯拉夫新杨工厂化养猪场,共15个世代的6245头纯繁长白母猪的繁殖记录。研究性状为头胎总产仔数和头胎断奶仔数。发现在群体均数、群体方差以及在群体分布的变化趋势方面理论模拟结果与实际分析结果颇为一致。还发现,仅由加性基因控制的性状同由加性和非加性(完全显性和超显性)、基因控制的性状,在群体均数与群体方差两者变化关系,以及选择反应的变化趋势方面各有特点。本研究表明,长期选择作用下的群体均数、群体方差、群体分布以及选择反应等参数的变化,其内在联系的本质在于控制所选性状基因频率的变化。若根据控制所选性状的各类基因数目、频率及其对表现作用的大小来估测选择后代的群体生产性能可能更准确,随着基因工程的不断发展,这将会得到实现。

LONG-TERM SELECTION AND TRENDS OF POPULATION CHANGES IN SOME PARAMETER

The orefical simulations were carried out and records for 6245 firstparity litters farrowed from 1970 through 1984 or from generations 0 to 14 in purebred Landrace swine on the Swine Farm "N. Topola" in Yugoslavia were, analyzed to study how long-term selection changes a population in theory and in practice. Traits examined included litter size at birth and at 21 days of age. It has been found that there are identical trends in the changes of population means, population variances and population distributions between results from the theoretical simulation and from practical data in the successive generations under long-term selection. The trait controlled by only additive genes is different from that determined by additive and nonadditive genes in the relationship between population means and population variances and in the response to selection. The results seem to indicate that population changes under the long-term selection depend on the changes of frequencies of desired genes, which determine the selected trait. And, it would be more exact to estimate population performance according to numbers of various type genes, their frequencies and effects for trait This would come true as the further development of gene engineering