Pikeperch (Sander lucioperca) is a native fish species in the European and Asian basin, representing high natural and economical value. However, our information on the genetic background and diversity of European populations is still limited, despite of that the production and the number of bread stocks has increased significantly in the last decade. Our aim was to develop new useable species-specific microsatellites and compare genetic diversity of ten pikeperch population from the Danube drainage basin. Thirty-four novel species-specific DNA markers were isolated and seven polymorphic microsatellite markers were selected for the population genetic analysis. The results indicated strong anthropogenic effects among the populations. The F ST estimated by the method of Weir and Cockerham (1984) was 0.214, showing moderate genetic difference among the populations. The STRUCTURE analysis and the neighbourjoining dendrogram are showing the same result: the ten examined populations aggregate six genetically distinct units. Significant lack of heterozygosity was detected in most of the populations. Presumably, it is indicating the effects of human activities and such as vigorous stocking of natural waters. In addition, the effect was proved that fish stocks involved in pond culture and RAS rearing do not necessarily originated from the geographically closest natural populations.
The African catfish or sharp tooth catfish (Clarias gariepinus) is one of the important species (due to its high environmental tolerance and easily controllable breeding habits) that can significantly contribute to reducing hunger in many countries. It is farmed in numerous African, Asian, and European countries. Moreover, during the last decades its production has grown significantly worldwide. Currently, following the carp, this species is produced in the second largest volume in Hungary. Despite its economic importance, the stocks have been maintained without genetic control or guided breeding. Molecular genetic data on bred populations or strains are very limited. In order to investigate the genetic structure of the stocks, 49 new microsatellite markers were characterized and tested on 32 individuals from a Hungarian farmed stock. All these markers were polymorph. The number of alleles per locus ranged from 2 to 11. The observed and expected overall heterozygosities were between 0.519 and 0.544 respectively and the overall inbreeding coefficient (Fis: 0.063) does not reveal the presence of inbreeding. However, 63% of the markers showed significant deviations from HWE. The results suggest that the maintenance of genetic variation within the stock require high attention in closed bred populations. These new markers provide a useful tool for population and conservation genetics of natural and bred African catfish populations.
The Eurasian perch (Perca fluviatilis Linnaeus, 1758) is native to almost entire Eurasia. For over the last two decades, this species became an important candidate for intensive freshwater aquaculture due to its high consumer’s acceptance and overall market value. Hence, the intensive production of Eurasian perch has increased considerably allowing effective domestication; there is still a need for the development of effective selective breeding programmes allowing its further expansion. This process, in turn, can be significantly facilitated by molecular genetics. The genetic information of Eurasian perch and its populations is limited. Up to date information of regarding genetic diversity of many populations is still missing, including microsatellites for Eurasian perch, which could be useful during the selective breeding programmes allowing parental assignment and/or to follow heritability of desired traits. In this study, we have developed and characterized new polymorphic microsatellites. Subsequently, those 12 markers have been used further to compare two Hungarian and one Polish Eurasian perch populations. The Hungarian stocks had high genetic similarity (with low diversity), as we assumed, while the Polish population differed significantly. All populations deviated significantly from the Hardy–Weinberg equilibrium, and heterozygote deficiency was detected in all, showing the presence of an anthropogenic effect.
BackgroundAnalyses of the control region sequences of European brown trout populations’ mitrochondrial DNA have revealed five main evolutionary lineages (Atlantic, Danubian, Mediterranean, Adriatic, Marble) mostly relating to the main water basins; however, the hybridization between lineages were increasingly reported. Due to the hydrogeography of Hungary, wild populations should theoretically belong to the Danubian lineage, however, this has not been verified by genetic studies.MethodsIn our study multiple molecular marker sets (mitochondrial sequence, microsatellites, PCR-RFLP of nuclear markers and sex marker) were used to investigate the genetic composition and population genetics of the brown trout populations in two broodstocks, six wild streams in Hungary and one Serbian population.ResultsThe admixture of Atlantic and Danubian lineages in these populations, except the Serbian population with pure Danubian origin, was observed by control region sequences of mitochondrial DNA and PCR-RFLP markers in the nuclear genome, and one unpublished Danubian haplotype was found in Hungarian populations. A sex-specific marker revealed equal gender ratio in broodstocks and Kemence stream, whereas in other wild streams the proportion of female individuals were less than 50%. Structure and principal component analyses based on the alleles of microsatellite loci also revealed overlapping populations, however the populations were still significantly different from each other and were mostly in Hardy-Weinberg equilibrium.DiscussionStocking and migration can have a significant genetic impact on trout populations of wild streams, however there are no guidelines or common practices for stocking of small streams in Hungary, thus the genetic background of these populations should be considered when developing conservation actions.
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