杜洛克、长白和大约克夏纯种猪微卫星多态性分析

Analysis of Genetic Polymorphism in Duroc,Landrace and Yorkshire Pigs Using Microsatellite Markers

利用8个微卫星标记对杜洛克、长白、大约克夏、长大、杜长大5个种群的等位基因的频率、基因杂合度、平均杂合度、多态信息含量，F-统计量、迁移率以及3个纯种之间的遗传距离进行分析。研究结果表明：各群体的平均基因杂合度存在一定差异，杜长大猪群的平均杂合度高于长大猪群，高于3个纯种群的平均杂合度；3个纯种猪群中，杜洛克平均基因杂合度最低，为0．6488，大约克夏平均基因杂合度最高，为0．7233；平均多态信息含量也出现了相同的结果。聚类结果显示：长白、大约克夏间的距离最大，长白、杜洛克间的距离最小，表明长白与大约克夏交配后与杜洛克杂交产生的杂种优势最大，这与实际的杂交组合一致，遗传距离可以预测杂种优势。Fst衡量等位基因频率群体间方差，显示群体总变异的约有3．9％-11．4％来自种群间，而剩余的88．6％～96．1％则来自种群内，Fst可以作为选育程度的一个指标。

The allele frequencies, heterozygosity, mean heterozygosity, polymorphism informatiom content （PIC） of Duroc, Landrace, Yorkshire, Landrace x Yorkshire ,Duroc x Landrace x Yorkshire and Nei＇s genetic distance,F-statistics and migration rate were studied in three pure breeds using eight microsatellite DNA markers. There were differences among allele frequencies at eight microsatellite loci in five populations. Mean heterozygosity in Landrace × Yorkshire was higher than those in three pure breeds and Duroc ×Landrace ×Yorkshire was the highest （0. 762 2）. Among three pure breeds, mean heterozygosity of Landrace was the lowest（0. 648 8） ,and that of Yorkshire was the highest（0. 723 3）. Similar results were also found in PIC. Cluster analysis between three pure breeds indicated that Landrace and Yorkshire had large genetic distance according to standard genetic distance of Nei＇s, and genetic distance between Duroc and Landrace was the nearest. It suggested heterosis would be the highest through hybridization between Landrace and Yorkshire and then Duroc. Genetic distance could be used to predict the heterosis. The Fst statistics showed that 3.9% - 11.4% and 88.6% - 96. 1% of total variation came from between and within population, respectively. Fst, could be used as index for breeding degree.