吉富品系尼罗罗非鱼选育过程中遗传变异的微卫星分析

Analysis of genetic diversity of GIFT strain Nile tilapia (Oreochromis niloticus) during selection processing by microsatellites

采用微卫星标记技术对选育新品种新吉富罗非鱼(F8-9)群体、基础群体(F0)、以及选育中群体(F6-7)在选育过程中出现的遗传变异进行观察与分析。19个微卫星位点扩增后的等位基因数为3～11个,随引物不同而异,合计得到115个等位基因,大小在70～270bp之间。五群体平均基因多样性指数分别为,F0:(0.3083±0.1834)、F6:(0.2982±0.1889)、F7:(0.2923±0.1898)、F8:(0.2572±0.1923)、F9:(0.2743±0.1597),表明随着选育的进展,群体呈现出纯化趋势。AMOVA分析表明,在总遗传变异中,93.24%来自选育群体内,仅6.67%来自选育群体间。群体间的校正偏差后相似性系数在F0与F6、F7之间分别为0.9435和0.9422,相对较高;而在F0与F8、F9之间分别为0.9332和0.9303,相对较低。遗传距离在F0与F6、F7之间分别为0.0581和0.0595,相对较小;而在F0与F8、F9之间分别为0.0691和0.0722,相对较大。配对比较Fst值在F0与F6、F7之间分别为0.03768和0.06437,平均值为0.05103;而在F0与F8、F9之间分别为0.06093和0.07587,平均值为0.06840,有所提高。这些指标的分析结果表明,经9年9代选育,已在罗非鱼世代间造成程度虽小但却可监测到的遗传分化;同选育群体F6-7相比,”新吉富罗非鱼”(F8-9)在遗传上更为稳定。

19 microsatellites were used to observe and analyse the genetic variation of selected generations of GIFT tilapia （ Oreochromis niloticus ）. During selection processing, 19 polymorphic microsatellite loci were used. Total of 115 alleles were found among the five generations of 100 individuals. The number of alleles per locus ranged from 3 to 11, with allele size ranging from 70 to 270 bp. The average gene diversity indices of the base population Fo, and selected generations, F6, F7, F8, F9 were （0.3083 ± 0. 1834）, （0.2982±0. 1889）, （0.2923 ± 0.1898 ）, （0.2572 ± 0.1923）, （0. 2743 ± 0. 1597）, respectively, which suggested that the selected populations were getting pure generation by generation. AMOVA analysis showed that there were 93.24% of total genetic variation derived from genetic diversities within population, 6.67% from among populations. Nei＇ s（1978） genetic identity between F0 and F6, F7 was 0.943 5 and 0.942 2, between F0 and F8, F9 was 0.933 2 and 0.930 3, respectively, which was relatively lower. Nei＇s（1978） genetic distance between Fo and F6, F7 was 0.058 1 and 0,059 5, between F0 and Fs, F9 was 0.069 1 and 0.072 2, which was relatively larger. Pairwise Fst values were 0.037 68, 0. 064 370 between Fo and F6, F7, respectively, averaged 0.051 03; and 0. 060 93, 0. 075 87 between F0 and Fs, Fg, respectively, averaged 0. 068 40. These results showed that there were a minimal, but could be monitored genetic differentiation caused by nine generation of selection in Nile tilapia, the genetic structure of the ＂New GIFF tilapia＂ F8-9 was more stabler than F6-7.