Genetic structure and demographic history of endangered Alburnus tarichi (Güldenstädt, 1814) populations from Lake Van basin in Turkey inferred from mtDNA analyses.

Genetic diversity, genetic structure, and demographic history of the endemic and endangered cyprinid species Alburnus tarichi based on samples from 17 populations consisting of resident and potamodromous specimens from the Lake Van basin in eastern Turkey were analyzed using two mitochondrial DNA markers. A. tarichi populations in the Lake Van basin are genetically heterogeneous, as indicated by the high haplotype and low nucleotide diversity of 1233 bp of the 16S rRNA marker (44 haplotypes; 70 polymorphic sites, haploid diversity (Hd) = 0.9130, π = 0.0032) and 1140 bp of the cyt b marker (47 haplotypes; 82 polymorphic sites, Hd = 0.9339, π = 0.0057). Clades were separated by average sequence divergences of 1.94% (II vs. III), 1.80% (I vs. III), and 0.66% (I vs. II). Based on these clades, AMOVA analysis revealed that 80.76% of the total variation occurred among populations, 10.74% occurred within populations, and only 8.50% occurred between populations within groups for the concatenated 16S rRNA-cyt b sequences. Pairwise FST values varied from 0.0167 to 0.9705 for the concatenated 16S rRNA-cyt b dataset, emphasizing the high genetic variation among populations. The time since the endemic tarek populations split from their last common ancestor has been dated to 5.647 Ma (95% highest posterior density: 4.183-7.011 Ma) in the Messinian Stage. Recent population expansion for tarek populations has been determined by neutrality tests and mismatch distribution analyses. The results of this study provide valuable information on the genetic population structure, conservation, and management of this species.

Population genetic structure of turbot (Scophthalmus maximus L., 1758) in the Black Sea.

Turbot, Scophthalmus maximus, is a commercially important demersal flatfish species distributed throughout the Black Sea. Several studies performed locally with a limited number of specimens using both mitochondrial DNA (mtDNA) and microsatellite markers evidenced notable genetic variation among populations. However, comprehensive population genetic studies are required to help management of the species in the Black Sea. In the present study eight microsatellite loci were used to resolve the population structure of 414 turbot samples collected from 12 sites across the Black Sea. Moreover, two mtDNA genes, COI and Cyt-b, were used for taxonomic identification. Microsatellite markers of Smax-04 and B12-I GT14 were excluded from analysis due to scoring issues. Data analysis was performed with the remaining six loci. Loci were highly polymorphic (average of 17.8 alleles per locus), indicating high genetic variability. Locus 3/20CA17, with high null allele frequency (>30%), significantly deviated from HW equilibrium. Pairwise comparison of the FST index showed significant differences between most of the surveyed sampling sites (P < 0.01). Cluster analysis evidenced the presence of three genetic groups among sampling sites. Significant genetic differentiation between Northern (Sea of Azov and Crimea) and Southern (Turkish Black Sea Coast) Black Sea sampling sites were detected. The Mantel test supported an isolation by distance model of population structure. These findings are vital for long-term sustainable management of the species and development of conservation programs. Moreover, generated mtDNA sequences would be useful for the establishment of a database for S. maximus.