“新吉富”罗非鱼选育F10～F13遗传变异微卫星分析

Genetic variations among the recent selected generations F10—F13of NEW GIFT strain Nile tilapia（Oreochromis niloticus）by SSR analysis

摘要:

利用微卫星分子标记技术,对“新吉富”罗非鱼选育后期的F₁₀、F₁₁、F₁₂、F₁₃ 4个世代群体的遗传结构及异同进行了分析。结果表明：13个微卫星位点扩增后，共得到78个等位基因，扩增片段长度大小在100～295 bp之间，4个选育世代的平均有效等位基因数（Ne）为2.84～3.27，平均期望杂合度（He）为0.627 1～0.676 2，平均多态信息含量（C_PI）为0.567 6～0.622 9，3个遗传参数都一致呈现随着选育世代数累进而稳定下降的趋势，表明“新吉富”罗非鱼在长期选育过程里越来越趋于纯化之中。另一方面，4个选育世代两两间遗传分化F_ST值为0.019 07～0.133 54，世代间亦存在中等程度的遗传分化，显示“新吉富”罗非鱼的选育技术路线（黄河、长江及珠江3大农业生态区同步选育、适时交流，始终注意保持繁育群体的有效大小，严格的择优四步程序等）可使选育群体保持较丰富的遗传变异水平，有利于长期选育的持续开展。

Abstract:

Simple Sequence Repeats（SSR）marker analysis was used to measure the genetic structure and genetic differentiation of four successively selected generations（F₁₀,F₁₁,F₁₂,F₁₃）of NEW GIFT strain Nile tilapia（Oreochromis niloticus）. The results showed that: total of 78 alleles（100-295 bp）were found among the four populations of 120 individuals with 13 polymorphic microsatellite loci. The mean number of effective alleles of four generations ranged from 2.84 to 3.27, the average polymorphism information content and the expected value of mean heterozygosity varied from 0.567 6 to 0.622 9 and from 0.627 1 to 0.676 2 in four selected generations, respectively. Three genetic parameters all indicated the same tendency that they have been steadily decreasing with the increasing of selected generations, which proved that the purifying experience of NEW GIFT strain Nile tilapia（Oreochromis niloticus）was still continuing in the course of long-term selective breeding. On the other hand, pair wise F_ST values between the two arbitrary generations ranged from 0.019 07 to 0.133 54, which indicated that the selective breeding generations also generated moderate genetic differentiation. The above results showed that our applied breeding technique strategy (synchronized selection at Yellow River, Yangtze River and Pearl River ecosystems, exchange periodically, keep effective breeding number, as well as strict superfish four-steps selection proceeding)for the NEW GIFT strain Nile tilapia（Oreochromis niloticus）could enable the selective breeding populations to maintain abundant genetic variation, which would be beneficial to the sustainable development of long-term selective breeding.