Assessment of Genetic Variability and Microsatellite Analysis of Pacific Oyster (Crassostrea gigas) After Artificial Selection of the Shell Width

Abstract:

In this study we investigated how mass selection would affect the genetic properties of the successive strains such as the fast growth in the shell width. Ten polymorphic microsatellite loci were analyzed to examine the genetic variation within a population, in one base stock, and in two successive mass selection lines of Pacific oyster (Crassostrea gigas). All microsatellite loci in the three groups showed high polymorphism, demonstrated by a large number of alleles per locus (NF0=16.5; NF1=12.2; NF2 =12.8) and high polymorphism information contents (Pic F0 = 0.9068, Pic F1 = 0.8982, Pic F2 = 0.8836). In all population-locus cases (3 populations × 10 loci), the observed heterozygosity values (Ho) of the 10 loci were lower than the expected values (He) (He=0.8954-0.9297, Ho=0.5775-0.6484). Twenty-four cases deviated from the Hardy-Weinberg equilibrium (P<0.05). The values of Fis ranged from 0.152 to 0.233, resulting in heterozygote deficiencies at the 10 loci in each population. Fst ranged from 0.0093 to 0.0245, indicating a weak genetic differentiation among the populations. The results suggested that the successive selection for rapid growing shell width might not reduce the genetic diversity. Therefore, the growth traits of C. gigas could be improved over generations under successive selection strains