Genetic structure and demographic history of whiting Merlangius merlangus (Linnaeus, 1758) populations distributed in Turkey inferred from variation in mitochondrial DNA sequences

The genetic diversity, structure, and demographic history of the economically important and overfished Gadidae species Merlangius merlangus were investigated using the non-coding mitochondrial Control Region (CR) from five different sites in the Sea of Marmara and the Black Sea in Turkey. The populations of M. merlangus were found to be genetically diverse, with 14 haplotypes and 15 polymorphic regions. The overall haploid diversity was 0.910 +/- 0.024, and the nucleotide diversity was 0.003 +/- 0.0003. Genetic distances between populations varied between 0.13% and 8.02%, while genetic distances within M. merlangus populations varied between 0.09% and 0.42%. Principle Coordinates Analysis showed that Marmara, Black Sea, and Karadeniz Eregli populations were clearly separated. Pairwise FST values varied from 0.12 to 0.69, highlighting high genetic variation among populations. The Black Sea and Marmara lineages of M. merlangus diverged from the North Sea lineage 1.65 (1.08-2.29) mya, whereas the separation between the Atlantic lineage occurred about 0.84 (0.51-1.2) mya. The recent expansion of the whiting population was identified through neutrality tests and mismatch distribution analyses. This study provides important insight into the genetic structure, conservation, and management of this species.