Estimation Of Heritability For Growth-related Traits In Juvenile Japanese Flounder (Paralichthys Olivaceus)

Estimation of heritability for economically important traits is necessary in fish selection and breeding programs, as it could provide valuable information for determining reasonable breeding plans and predicting selection response.A factorial mating design consisting 10 sires and 3 dams , generating 10 sire half-sib, 3 dam half-sib and 30 full-sib families, was employed to estimate heritability for growth-related traits in 40-day Japanese flounder Paralichthys olivaceus, using 9 microsatellite markers for parentage assignment. Beside, The difference between parents contributing to reproduction and the real effective population size (Ne) was detected in the factorial cross. The results are as follows:The markers presented high or moderate polymorphism in 13 bloodstocks, with 10 alleles per loci and 4 unique alleles per loci in average. Out of 346 offspring, 65.6% (227) could be assigned to one single parent using 5 polymorphic loci(Po91,Po1,Po56,Po20,Poli23). The rest 119 individuals were genotyped by another 4 loc(iPo89,Poli121,Po42,Po13), and 72 individuals were successfully assigned. Efficiency of these markers was about 86%, and the unique alleles play an important role in the assignment.There was no difference between the application results showed in non-denaturalized polyacrylamide gel electrophoresis on highly degraded DNA and non- degraded DNA, using the same microsatellite loci under the same condition. This approved a fact that microsatellites were relatively stable in degraded DNA.It was different between parents contributing to reproduction. The highest and the lowest paternal parent contributions were 5.8% and 14.3%, respectively; the highest and the lowest maternal parent contributions were 18.5% and 50.6%, respectively.The relatively imbalance family sizes resulted in declined effective population size (Ne). With the assumption that all sires and dams have the same contribution rate, the expected Ne was 9.23, while the real Ne was 7.44, a reduction of 19%.Heritability based on sire components for total length, body length, body depth, head length, caudal peduncle length, caudal peduncle depth and body weight was 0.440±0.137, 0.360±0.128, 0.293±0.123, 0.181±0.101, 0.262±0.073, 0.349±0.101, 0.157±0.052, respectively. The proportion of additive variance concluded that genetic improvement for growth-related traits through selective breeding might gain success.