凡纳滨对虾进口亲虾子一代群体的遗传变异分析

Genetic variation analysis among first filial generation of introduced Litopenaeus vannamei stocks

【目的】明确凡纳滨对虾(Litopenaeus vannamei)进口亲虾直接繁殖子一代种苗群体的遗传变异情况,旨在评估遗传特征与养殖生产性能的关联性,为我国养殖对虾优质种苗大数据建设及质量评估体系的完善提供基础数据支持。【方法】以来源于正大神湾虾苗场的Stock 1~Stock 5群体、正大漳浦虾苗场的Stock 6群体、海尚种苗培育基地的Stock 7和Stock 8群体及中海水产种苗科技有限公司的Stock 9群体等9个不同批次凡纳滨对虾进口亲虾子一代种苗为研究对象,利用11个微卫星分子标记(M1、Pvan1758、Pvan1815、HLJN-008、HLJN-023、TUMXLv7.121、TUMXLv8.256、TUMXLv9.43、TUMXLv10.312、TUYFLvL16.1a和TUDGLv1-3.224)对不同凡纳滨对虾种苗群体进行遗传变异分析。【结果】9个凡纳滨对虾种苗群体的等位基因数(Na)、有效等位基因数(Ne)、观测杂合度(Ho)、期望杂合度(He)、Shannon’s信息指数(I)和多态信息含量(PIC)的平均值分别在5.5455~8.8182、3.2795~5.4735、0.3769~0.5182、0.6189~0.6948、1.2823~1.6092和0.5863~0.6646,即各凡纳滨对虾种苗群体均具有较高的遗传多样性,具体排序为Stock 3>Stock 2>Stock 4>Stock 5>Stock 7>Stock 6>Stock 9>Stock 8>Stock 1。在9个凡纳滨对虾种苗群体中有91.82%的遗传变异源自群体内,仅有8.18%的变异源自群体间。Stock 2、Stock 3、Stock 4和Stock 5等4个群体间及Stock 7群体与Stock 8群体间的遗传分化系数(Fst)均小于0.05(0.0079~0.0371),即群体间无遗传分化,而其他群体间表现为轻度遗传分化(0.05<Fst<0.15)。基于Nei’s遗传距离,9个凡纳滨对虾种苗群体大致可划分为三大分支,第一分支包括Stock 1~Stock 6群体,第二分支由Stock 7群体和Stock 8群体组成,而Stock 9群体独立为第三分支。【结论】不同批次凡纳滨对虾进口亲虾子一代种苗群体的遗传特征存在明显差异,各群体间的遗传距离随着采样时间和地点的改变而发生明显变化,且这些遗传背景差异可能会造成不同群体在养殖生产性能方面产生差异。

【Objective】The main purpose of this study was to analyze and assess the genetic diversity of first filial ge-neration of Litopenaeus vannamei,in order to evaluate the correlation between its genetic characteristics and aquaculture production performance,and provide basic data support for the big data construction and establishment of quality evalua-tion system of high-quality post-larvae in China.【Method】The objects were L.vannamei Stock 1-Stock 5 from Zhengda Shenwan shrimp larvae farm,Stock 6 from Zhengda Zhangpu shrimp larvae farm,Stock 7 and Stock 8 from Haishang shrimp larvae farm,Stock 9 from Zhonghai aquatic larvae culture company.The genetic variation of nine first filial gene-ration stocks were investigated using eleven microsatellite DNA markers(M1,Pvan1758,Pvan1815,HLJN-008,HLJN-023,TUMXLv7.121,TUMXLv8.256,TUMXLv9.43,TUMXLv10.312,TUYFLvL16.1a and TUDGLv1-3.224).【Re-sult】This paper showed that the average values of the number of alleles(Na),number of effective alleles(Ne),observed heterozygosity(Ho),expected heterozygosity(He),Shannon’s diversity index(I),and polymorphism information con-tent(PIC)were among 5.5455-8.8182,3.2795-5.4735,0.3769-0.5182,0.6189-0.6948,1.2823-1.6092 and 0.5863-0.6646,respectively.That presented a high genetic diversity of these filial generation of introduced L.vannamei stocks,and according to the richness,they ranked as follows:Stock 3>Stock 2>Stock 4>Stock 5>Stock 7>Stock 6>Stock 9>Stock 8>Stock 1.AMOVA analysis indicated that the genetic variation within stock was 91.82%and the remaining 8.18%of the variation occurred among stocks.The genetic differentiation among Stocks 2-5 and among Stocks 7-8 showed a low level based on their Fst values(0.0079-0.0371),which were lower than 0.05,whereas the other stocks had no genetic dif-ferentiation(0.05<Fst<0.15).Based on Nei’s genetic distance,the nine stocks could be roughly divided into three branches:the first branch including Stock 1-Stock 6 stocks,the second branch being composed of Stock 7 and Stock 8,and the third branch only included Stock 9.【Conclusion】These findings indicated that different batches of first filial generations have distinct genetic characteristics.Dramatically,genetic distance of first filial generations are clearly fluctuated with the breeding farm and breeding time.Changes of genetic background might directly affect the shrimp traits in subsequent farming.