This study was conducted to analyze the genetic diversity of parents population of olive flounders collected for long-term breeding and to verify the results of the estimation of genetic parameter by growth stage and of the genetic evaluation. For the analysis of genetic diversity, the number of alleles by collected locations, the observed heterozygosity, the expected heterozygosity, or polymorphism information content of 443 parent fishes; and, the descriptive statistics by collected locations were examined and the regression coefficient of distribution curve was estimated. In the case of 170 days olds, the data on the growth-related traits for 3,113 fishes; in the case of 330 days olds, the data for 7,192 fishes; and in the case of 540 days olds, the data for 1,189 fishes was used to estimate the genetic parameters of the growth-related traits by growth stage. For testing the results of the genetic evaluation, the data on the growth-related traits for 518 progenies produced by mating superiority parents and inferiority parents is described below.
1. According to three DNA markers used in the analysis, the mean expected heterozygosity by collected location is distributed from 0.841(CA) of the lowest point to 0.936(WG) of the highest point. The mean expected heterozygosity of the total group is shown high as 0.892; it was especially estimated in wild populations than the average value, so genetic variability within group was found relatively large.
2. When the expected heterozygosity by collected locations analyzed with KOP02 marker was examined, the difference in heterozygosity was shown in the order of WG, WT, WE, WB, CB, CD, CC, and CA. The values of WG and WT were 0.941 and 0.931, respectively, shown as the groups with high genetic diversity, while the values of CA and CC were 0.770 and 0.800, respectively, shown as the groups with low genetic diversity.
3. When the expected heterozygosity by collected locations analyzed with KOP26 marker was examined, the difference in heterozygosity was shown in the order of WB, WG, WE, WT, CC, CD, CA, and CB. The values of WB and WG were 0.923 and 0.921, respectively, shown as the groups with high genetic diversity, while the values of CB and CA were 0.840 and 0.890, respectively, shown as the groups with low genetic diversity.
4. When the expected heterozygosity by collected locations analyzed with KOP27 marker was examined, the difference in heterozygosity was shown in the order of WG, WE, WB, WT, CB, CC, CA, and CD. The values of WG and WE were 0.946 and 0.940, respectively, shown as the groups with high genetic diversity, while the values of CD and CA were 0.760 and 0.780, respectively, shown as the groups with low genetic diversity. Overall, the cultured populations showed the low values in the number of alleles and heterozygosity, indicating that its stabilization process of genetic composition is advanced more than that of the wild population.
5. When the distributions of body weight and body shape of parent populations were examined by collected locations, it was found that, in the case of body weight, the cultured population is distributed more broadly than the wild population; but, on the contrary, in the case of body shape, the wild population is distributed more broadly. This kind of difference in distribution between groups could be the measurement to predict population diversity.
6. Regarding the effect of production batch for the growth-related traits among 170 days olds, body weight, total length, body height and condition factor were found significantly high in Batch 2, while body shape was found significantly high in Batch 1 (p<0.01). In terms of the growth-related traits of 330 days olds and 540 days olds, all traits were found significantly high in Batch 1 (p<0.01).
7. When the effect of sex for the growth-related traits among 330 days olds was examined, body weight, total length, body height, and body shape were found significantly high among the females, while condition factor was significantly high among the males (p<0.01). Regarding the effect of sex for the growth-related traits among 540 days olds, body weight, total length, body height, and condition factor were significantly high among the females, while body shape is significantly high among the males.
8. In terms of the effect of mating sire and mating dam by growth stage, body weight, total length, body height, and condition factor were overall significantly high in the cultured population, while body shape was shown significantly high in the wild population.
9. For the growth-related traits among 170 days olds, heritabilities of body weight, total length, and body height were estimated as 0.564, 0.590, and 0.588, respectively; the shape-related traits, body shape and condition factor were estimated as 0.306 and 0.332, respectively. Among 330 days olds, heritabilities of body weight, total length, body height, body shape, and condition factor were estimated as 0.753, 0.751, 0.787, 0.438, and 0.368, respectively; for 540 days olds, heritabilities of body weight, total length, body height, body shape, and condition factor were estimated as 0.689, 0.678, 0.657, 0.595, and 0.498, respectively.
10. In terms of genetic correlations between growth-related traits for all growth stages, genetic correlations between body weight and total length, between body weight and body height, and between total length and body height were 0.969~0.981, 0.953~0.976, and 0.914~0.963, respectively, showing highly positive correlations. Genetic correlations between body weight and body shape, between body weight and condition factor, and between body shape and condition factor were found -0.238~-0.430, 0.373~0.623, and -0.705~-0.740 respectively.
11. For same traits of body weight, body shape, and condition factor, genetic correlations were 0.848, 0.902, and 0.775; phenotypic correlations were 0.707, 0.672, and 0.564; and, rank correlations were 0.688, 0.667, and 0.553, respectively, between 330 days olds and 540 days olds.
12. Regarding the least-squares means of body weight and total length by each mating group, the group produced by mating between superiority parents (S×S) were 145.58±1.76g and 22.44±0.10cm; the group produced by mating between superiority parent and inferiority parent (S×I) were 133.18±2.51g and 22.05±0.14cm; and, the group produced by mating between inferiority parents (I×I) were 114.04±2.13g and 21.08±0.12cm. All growth-related traits, body weight, total length, and body height, were significantly high in S×S group In terms of the least-squares means of shape-related traits by each mating group, S×S group had 2.756±0.005 and 12.74±0.04; S×I group had 2.817±0.008 and 12.20±0.06; and, I×I group had 2.863±0.007 and 11.90±0.05, respectively for body shape and condition factor. Body shape was found significantly high in I×I group, and condition factor was significantly high in S×S group.
13. Breeding values of the males used for mating, CC168, CC055, CC142, CC111 and CB067 by unit were estimated as 35.56, 33.09, 27.34, -12.60, and -21.05, respectively. The least-squares means of body weight for each mating sire were 148.54±5.14g, 139.86±3.47g, 138.74±4.61g, 118.31±3.66g, and 127.28±3.47g, respectively. Progenies of CC168 and CC055 with high breeding values were found to have the significantly higher values than progenies produced from other males. Breeding values of the females used for mating, CA014, CA093, CB003, CA053, CB105 and CA045 by unit were estimated as 20.81, 20.15, 13.11, 12.21, -8.08, and -12.29, respectively. The least-squares means of body weight for each mating dam were 142.42±4.77g, 130.00±8.37g, 141.29±4.17g, 141.07±5.70g, 125.21±2.39g, and 127.30±4.86g in the order of units from the highest breeding values to the lowest. Progenies of CA014 and CB003 with high breeding values were found to have the significantly higher values than progenies produced from other females.