Phylogeography and population dynamics of the Eastern Mediterranean whiting (Merlangius merlangus) from the Black Sea, the Turkish Straits System, and the North Aegean Sea

In this study, the taxonomic resolution and phylogenetic relationship of two presumed subspecies of Merlangius
merlangus, namely M. m. euxinus and M. m. merlangus, were investigated. In addition, the effect of the Turkish
Straits System on the evolutionary history and genetic structure of M. merlangus, was explored. The mitochondrial
cytochrome c oxidase subunit 1 and cytochrome b genes, and the nuclear recombination activating
gene-1 were analysed. Our results indicate no clear distinction between the two presumed subspecies, which is
attributed to the low resolution of recombination activating gene-1 and/or presence of potential gene flow
between the two subspecies. The temporal pattern of divergence between the two presumed subspecies related to
the Last Glacial Maximum (219 Kya), whereas the expansion of each main sampling location occurred after the
flooding of the Black Sea by salt water from the Mediterranean (5 Kya), following a period of stability.
Additionally, significant genetic differences are observed among the North Aegean samples and the collections
from the Turkish Straits System and the Black Sea, along with some significant structure among sampling sites
located in the Turkish Straits System and Black Sea. The lower genetic variability of the eastern Mediterranean
M. merlangus when compared to Atlantic ones might be due to a potential population bottleneck before the last
glacial period, a trend that is commonly found in these waters.