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

【Objective】 The main purpose of this study was to analyze and assess the genetic diversity of first filial generation 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 evaluation 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 generation 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).【Result】 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 content(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 F_st values(0.0079-0.0371), which were lower than 0.05, whereas the other stocks had no genetic differentiation(0.05<F_st<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.