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Genetic structure of modern and ancient swordfish populations from coasts of Turkey

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2017
Yüncü, Eren
In this study, partial mitochondrial DNA (mtDNA) and 8 microsatellite loci of swordfish collected from Northern Levantine Sea and Northern Aegean Sea were analyzed. Also same mtDNA region of ancient swordfish samples unearthed from Yenikapı excavation were sequenced. Obtained sequences were evaluated comparatively with the sequences from Balearic Sea, Ligurian Sea, Ionian Sea and Southern Aegean Sea, available in databases. Analysis of the molecular variance revealed a significant differentiation between Western (Balearic, Ligurian) and Eastern (Ionian, Southern Aegean, Northern Aegean, and Northern Levantine) Mediterranean. Eastern Mediterranean had lower diversity and lower long term effective population size (Ne) than Western Mediterranean. Generally, migration from Eastern Mediterranean to Western Mediterranean was higher. Ancient DNA (aDNA) population was slightly different from modern populations based on FST. However, continuity between aDNA/ Southern Aegean, aDNA/ Northern Aegean and aDNA/ Northern Levantine could not be rejected. Long term Ne and genetic diversity of aDNA were higher than Eastern Mediterranean and nearly equal to Western Mediterranean. FST, PCA and STRUCTURE results showed Northern Aegean and Northern Levantine were not differentiated based on microsatellites. All short term Ne’s calculated with various methods were less than 150 and MSVAR results showed dramatic Ne reduction in swordfish of both Northern Aegean and Northern Levantine, started 1240 and 599 years ago respectively. Mediterranean swordfish is considered as a single stock and only one conservation plan is offered. According to results, different conservation plans must be implemented for Eastern and Western Mediterranean and Eastern population, harboring the swordfish of Turkish coasts, is at great risk.