Genetic diversity among breeding populations of giant grouper (Epinephelus lanceolatus)

As the largest grouper species, the giant grouper (Epinephelus lanceolatus) exhibits rapid growth and significant competitive advantages, hence playing a crucial role in the development of the grouper industry. To understand the impact of artificial breeding and selection on the genetic diversity of E. lanceolatus, microsatellite molecular marker technology was employed in this study to investigate the genetic variation in five representative breeding populations collected from Guangdong, Hainan, and Fujian provinces in China. Genetic diversity analysis within the populations revealed an average number of alleles (N_a) of 7.326 (range: 6.375-8.380), an average observed heterozygosity (H_o) of 0.711 (range: 0.625-0.775), an average expected heterozygosity (H_e) of 0.705 (range: 0.684-0.734), and an average polymorphic information content (PIC) of 0.659 (range: 0.633-0.693). Notably, the breeding population from Xiang'an District, Xiamen, Fujian exhibited the highest genetic diversity. Analysis of molecular variance (AMOVA) revealed that 5.36% of the genetic variation was from between populations, while 95.45% was from between individuals. The genetic differentiation index (F_st) and genetic distance results indicated that the GC (Gancheng) and CP (Changpo) populations clustered together, joined by the AT (Aotou) population and then the XA (Xiang'an) population, with the HL (Huli) population forming a separate branch. The phylogenetic tree analysis showed overlapping of breeding populations without distinct geographical patterns. In conclusion, the breeding populations of E. lanceolatus in these three provinces exhibited high genetic diversity without evident signs of domestication. Overall, this study demonstrates that the breeding populations of giant grouper still maintain a high level of genetic diversity, with a low likelihood of decline due to inbreeding effects. However, the frequent occurrence of diseases and low survival rates in the breeding process may be attributed to imperfect artificial breeding techniques and inadequate aquaculture management. This research provides a theoretical basis for the genetic evaluation and artificial selection of E. lanceolatus. This study highlights the importance of maintaining genetic diversity within cultivated stocks to ensure the sustainability and productivity of aquaculture operations. Despite high genetic diversity observed, the management and traceability of breeding stocks need enhancement to safeguard against potential genetic bottlenecks. The findings underscore the need for ongoing genetic monitoring and responsible breeding practices in the preservasion of genetic health and viability of E. lanceolatus populations.