Patterns of allelic variation of polysomic SSR markers in population genetic assessment of Persian Sturgeon (Acipenser persicus Borodin, 1897) in Caspian Sea

Genetic structure of Acipenser persicus, in the Caspian Sea was studied using tetrasomic microsatellite markers. A total of 195 specimens of A. persicus breeders were collected from the sampling stations located in the five fishery catch zones as well as from the Sefidrud River in the south Caspian region. About 2 g of caudal fin samples was collected from each sturgeon specimen and preserved in 96% ethyl alcohol and then transferred to the genetic laboratory of the International sturgeon research Institute. Genomic DNA was extracted using the phenol-chloroform method. DNA quality and content was determined using spectrophotometry and agarose gel electrophoresis. Polymerase Chain Reaction (PCR) of genomic DNA fin samples was carried out using 8 pairs of microsatellite tetrasomic primers of which all of primers were polymorphic. All PCR products were electrophoresed on 6% polyacrylamide gel and stained with silver nitrate. Following the scoring of alleles, all parameters related to population genetics were calculated using the Phylip and Arliquin program and the phylogenetic relationship between samples was plotted using neighbor-joining tree. Number of alleles in A. persicus varied from a minimum of 8 (Zone 2) to a maximum of 14 alleles per locus (Sepidrud River). The observed and expected heterozygosity was between 0. 657 and 0. 784 respectively. Significant differences were detected between A. persicus specimens collected from Sepidrud River (P≤0. 001) and those collected in the south Caspian Sea. Significant differences were also detected between specimens caught in the eastern fishery zones and those caught in the western fishery zones of the south Caspian Sea (P≤0. 001).  Based on genetic criteria it is evident from the phylogenetic tree plotted that A. persicus specimens collected from the Sepidrud River belonged to one cluster and all other specimens belonged to a separate cluster. Based on the results obtained it may be concluded that three independent populations of A. persicus are found in the Caspian Sea which include the Sepidrud population, and the population of the fishery zone three in which this calls for further investigations on the genetic structure.