Genetic diversity and microsatellite patterns in hatchery-produced Thai abalone Haliotis asinina

Abstract

Genetic diversity of hatchery-propagated stocks (G8, N = 102 and B, N = 120) and a wild sample originating from Talibong Island (N = 14 - 25) of the tropical abalone (Haliotis asinina) were examined at 5 microsatellites loci. A total number of alleles per locus at CUHas2, CUHas3, CUHas8, Haµ2J and Haµ13 across all samples were 9, 14, 14, 7 and 6 alleles, respectively. Sizes of allele distribution were 310 - 352, 155 - 183, 144 - 220, 228 - 240 and 124 - 135 bp, respectively. The number of CUHas2, CUHas3, CUHas8 and Haµ13 alleles in the hatchery-propagated abalone was greater than that of the Talibong sample. In contrast, that of the Haµ2J locus in the wild sample (6 alleles) was greater than the hatchery samples (4 alleles). The discrimination capacity was 0.175 ± 0.096, 0.216 ± 0.133 and 0.349 ± 0.201 for G8, B hatchery samples and the Talibong sample, respectively. Observed heterozygosity in the respective hatchery samples was 0.69 ± 0.308 and 0.56 ± 0.241 which is slightly greater than that of the Talibong sample (0.52 ± 0.180). The power of discrimination, power of exclusion and matching probability of this set of microsatellites in G8 (0.99989445, 0.9936054 and 0.0001055), B (0.9999898, 0.9137856 and 0.0000102), combined hatchery samples (0.9999961, 0.9606105 and 0.0000039) and Talibong (0.9994288, 0.7894797 and 0.0005712) samples were comparable. The number of contributed founders of the previous generation was inferred from offspring genotypes and found that 10 males and 10 females contributed for each hatchery sample. The estimated effective number of population size (Ne) and inbreeding coefficient of each hatchery stock was 20 individuals and 2.5% per generation. Results from this study indicated relatively high levels of genetic diversity but limited numbers of contributed founders from the previous generation of the hatchery stock of H. asinina.In addition, preliminary association analysis between microsatellite genotypes and the body weight of the hatchery B sample was examined. A simple linear regression indicated significant correlation between those factors at the locus Haµ13 (P < 0.05) but not other loci (P > 0.05). Interestingly, abalone carrying homo- and heterozygotic status of the 128 allele had a lower body weight (3.477 ± 0.735 – 7.430 ± 0.099) than the average weight of the B sample (7.60 ± 2.758, N = 280). Significant differences between the body weight of the B sample having different genotypes (e.g. between homozygotes and heterozygotes carrying the 124 alleles and those carrying the 128 allele) were found when analyzed by ANOVA and the post hoc Duncan’s new multiple range test (P < 0.05). The possible correlation between microsatellite genotype and phenotype (the body weight) was preliminary illustrated. Results on genetic diversity and possible correlation between genotypes and a phenotype (body weight) can be applied to promote the efficiency of breeding programs of this economically important species.