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Microsatellite-based genetic variability of common carp (Cyprinus carpio L.) populations in Croatia

Common carp (Cyprinus carpio L.) is economically important species for the aquaculture of Croatia. Fish farmers try to certify their stocks as genuine Croatian product ; therefore, the information on genetic diversity of these hatchery stocks is urgently required in order to sustain the quality of the broodstock. Sport fishing of common carp in open waters is often based on stocking from fish farms. Hence, the hybridization of feral populations becomes an increasing problem. The aim of our study was to explore genetic variability within and among five hatcheries and five feral populations from different Croatian regions using microsatellite DNA, a hyper-variable molecular marker. Fifteen microsatellite loci of 243 individuals from 5 hatchery and 5 feral populations have been analysed. A total number of 148 alleles were recorded across loci ranging from 6 at MFW12 and MFW17 to 20 at MFW20. However, the mean number of alleles per locus was remarkably low: from 2.2 in hatchery population Našice to 7.4 in feral population of the river Danube. Pairwise FST, values (0.136-0.424) were significant (P<0.01), demonstrating differentiation among populations. Markov chain method test showed that all the populations deviated from HWE (P < 0.05). After sequential Bonferroni correction only the Vrana lake was in HWE in all the loci but MFW20. Only the loci MFW9 and MFW29 were in HWE in all the populations. The factors that may result in genetic divergence and significant reduction of the observed heterozygosity were discussed. AMOVA results for 10 populations indicate that percentage of the variation among populations was 5.62%, which is lower than the variation within populations (61.26%). Genetic differentiations among 10 populations, as well as among feral and hatchery populations were both significant. In comparison to hatchery stocks higher genetic variability of the feral carp populations has been found. This is particularly important in the light of the global threat to the feral carp population. As five hatchery stocks of common carp have an important status in Croatian aquaculture, our results on genetic variability within/among them and the relationships among them can provide new background of knowledge in the population conservation and breeding programs.

Cyprinus carpio; microsatellites; Croatia

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