鞍带石斑鱼繁育群体的遗传多样性

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

摘要:

为了解人工养殖和选育活动对鞍带石斑鱼遗传多样性的影响。本实验采用微卫星分子标记技术，对广东、海南和福建3个省份共5个代表性采集点的鞍带石斑鱼繁育群体的遗传变异信息进行了研究。群体内遗传多样性分析结果显示，5个群体等位基因 (N_a)的平均数目为7.326 (6.375~8.380)，观测杂合度 (H_o)平均值为0.711 (0.625~0.775)，期望杂合度 (H_e)平均值为0.705 (0.684~0.734)，多态性信息含量 (PIC)平均值为0.659 (0.633~0.693)。其中，来自福建厦门翔安区的鞍带石斑鱼繁育群体遗传多样性最高。分子方差分析 (AMOVA)结果显示，5.36%的遗传变异来自群体间，95.45%来自所有个体间。群体间遗传分化指数 (F_st)及遗传距离结果显示，GC (感城)和CP (长坡)群体聚为一支，再与AT (澳头)群体聚为一支，然后与XA (翔安)群体聚为一支，HL (湖里)群体独立为一支。通过系统进化树分析显示，鞍带石斑鱼繁育群体交叉在一起，没有形成明显的地理格局分布。总之，这三省五地的鞍带石斑鱼繁育群体遗传多样性较高，没有明显的驯化迹象。研究表明，鞍带石斑鱼繁育群体仍具有较高的遗传多样性，品种受亲本近交影响而出现衰退的可能性不高，可排除因遗传因素导致的品种病害频发及养殖成活率低的原因。本研究可为鞍带石斑鱼种质评价和人工选育提供理论依据。

Abstract:

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.