Document Type : Research articles
The genetic variation of narrow-clawed crayfish (Astacus leptodactylus, Eschscholtz, 1823) from Caspian Sea including two sites (Astara and Kiashahr), Aras region, Anzali lagoon and three rivers (Chafrood, Masuleh, and Siah Darvishan) was evaluated and their genetic variation on the basis of DNA microsatellite loci was estimated. DNA from pleopods of 194 specimens extracted and was examined with six microsatellite markers. Genetic differences between the populations were discerned by pairwise comparison based on allelic distribution. The average numbers of alleles per locus ranged from 2 to 10, while the average observed heterozygosity (Ho) at various loci varied between 0.222 to 0.732, implying that a midway level of genetic variation. Among seven populations Siah Darvishan population displayed the highest level of variability in terms of heterozygosity. Tests of Hardy-Weinberg showed that the microsatellite loci deviated significantly in most populations indicating deficit of heterozygote. The results indicate that some of the above populations are significantly differentiated from one another based on pairwise FST estimates. Genetic distance based measures supported the clustering of Siah Darvishan, Chafrood and Astara may be genetically discrete from other narrow-clawed crayfish populations. The neighbor-joining dendrogram topology and multidimensional scaling approach (MDS) constructed on the basis of genetic distances among populations supported observed division between the populations. The non-significant differentiation between crayfish samples from the Anzali lagoon, Kiashahr and Masuleh can be explained by a relatively recent disconnection of these three populations and/or small amounts of gene flow. These results could give applicable information for cultivation of stocks and also for future genetic improvement of this commercial species by selective breeding program.