Population Genetic Analysis Of Red Spotted Grouper Epinephelus Akaara

The red spotted grouper Epinephelus akaara is of commercial importance and an attractive target fish for aquaculture. Presently, the red spotted grouper resources have been depleted to be in severe danger partly due to overfishing and its special particularities of reproduction. Population genetics of the red spotted grouper collected from East China Sea and South China Sea were studied by different DNA marker technologies. The results of this study will lay a theoretic foundation not only for the protection of the rare resources but also for the genetic breeding studies.In this study, in order to estimate the genetic structure and genetic diversity of E. akaara, 88 individuals sampled from 7 locations throughout the distribution range of E. akaara in China were analyzed by mtDNA, AFLP and SSR.1. Mitochondrial DNA variation was analyzed using sequence data from control region. Nucleotide diversity was high in E. akaara; The demographic history of E. akaara was examined using neutrality tests and mismatch distribution analyses, Molecular variance analyses and pairwise Fst revealed significant genetic structure among seven populations.2. 13 AFLP primers were used to investigate the genetic variation in E. akaara. A total of 941 loc were detected from 7 populations; the proportion of polymorphic loci, the Nei genetic diversity and Shannon genetic diversity index of 7 populations were 18.40%～47.70%, 0.0447～0.1429, 0.0665～0.2141, respectively. Molecular variance analyses and pairwise Fst showed significant genetic differentiation among seven populations. Some population specific bands were detected, these specific markers could be used for population identification.3. The genetic variations of 7 populations of E. akaara were assessed at 7 SSR loci. A total of 45 alleles were detected in the loci investigated, and the number of alleles at each polymorphic locus was in the range from 2 to 11, with an average value of 6.4. The Ho and He values of 7 populations were 0.2190～0.5079, 0.3683～0.6689, respectively. The genetic distance and pairwise Fst among populations varied from 0.0665 to 0.7093, 0.0048～0.2558, respectively. The pairwise Fst values showed most pairwises were statistically significant.Based on mtDNA, AFLP and SSR results, significant genetic differentiations among all populations were revealed, and 7 populations could be divided into two geographic populations. E. akaara compared to those in other teleosts assayed with the same techniques showed low genetic diversity.