Genetic Diversity of Barbels in Germany

So far, information on the genetic diversity for the common barbel (Barbus barbus) in Germany has been insufficient. Such information is essential for the future genetic management and stocking strategy of the barbel and for the protection of its genetic diversity. Accordingly, in this project, which was financed by the Federal Ministry of Food and Agriculture, Germany, we endeavoured to close this gap of knowledge and analysed several populations from different river catchments in Germany. This project was realized in close collaboration with Thomas Schiller (Inst. of Hydrobiology, TU Dresden).

In the years 2013 to 2015, we analysed 47 origins from six river catchments. Additionally, we developed a non-invasive approach to analyse forensically sampled DNA of barbel individuals. The genetic diversity of this tetraploid species was assessed using mitochondrial (control region) and nuclear microsatellite markers. The documented morphometric data and the results of the genetic analysis will be implemented into the AGRDEU Database for the Aquatic Genetic Resources of the Federal Office for Agriculture and Food

The analysis of the mtDNA has shown that the haplotype diversity in the river catchments Meuse and Weser was highest, whereas the lowest diversity was detected in the river catchment Danube and Elbe. The main part of the observed genetic variance for mtDNA and nuclear markers could be explained due to the genetic variation between individuals within the populations. Only about 1/4 (mtDNA) or 9% (nucDNA), respectively, of the observed variation was explained due to differences between the river catchments. 

Based on STRUCTURE analyses, especially individuals belonging to the river catchment Danube could never be clearly assigned to unambiguous groups, whereas within the river catchment Elbe and Rhine almost single, but differentiated genetic groups, could clearly be assigned to populations. 

In summary, the analysed barbel populations show a comparatively high level of variability with distinctive differences, but often with relatively low levels of population differentiation within and between river catchments. Therefore, stocking management should endeavour to use several individuals of the same genetic background for stocking measures.