Abstract:Largemouth bass (Micropterus salmoides) is a very important fish in commercial farming. As it is a carnivorous teleost, a large amount of forage fish and fish meal were used as food for largemouth bass every year. Residual forage fish and fish meal not only increase the costs of largemouth bass aquaculture, but also seriously pollute water bodies and farm lands. In order to reduce farming costs and protect the natural environment, selective breeding suitable for formulated feeds was carried out. In 2012, our research team selected the breeding population contain Youlu No.1 largemouth bass and introduced north largemouth bass. The genetic structure of largemouth bass breeding population was analyzed based on microsatellite DNA markers. A total of 240 individuals, from the foundation population (Sp0), the second generation group (Sp2), the third generation group (Sp3), and the fourth generation group (Sp4) (60 individuals per population) were assayed with 18 microsatellites. The results showed that a total of 44 alleles were identified, the numbers of alleles (Na) were 1~4 in four selected populations, respectively. The observed heterozygosity (Ho) of Sp0, Sp2, Sp3 and Sp4 was 0.4895, 0.4802, 0.4579 and 0.4206, respectively; the expected heterozygosity (He) was 0.4615, 0.4454, 0.4621 and 0.3916, respectively; the polymorphism information content (PIC) of Sp0, Sp2, Sp3 and Sp4 was 0.3791, 0.3659, 0.3764 and 0.3257, respectively. The F-statistics (Fst) value is between 0.01612 and 0.16162, and the genetic distance (Da) is between 0.0249 and 0.1434. Partitioning of the genetic variation revealed that only 8.38% genetic variation was among the populations, and the other genetic variation was within the populations. The results showed that the artificially selected population using formulated feeds showed moderate genetic diversity, and still had great potential for future selective breeding.
