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My bachelor thesis

Genetic structure of European sculpin (Cottus gobio L.) populations in the contact area of Danube, Odra and Elbe river basins


            In this study, an allozyme survey was used to compare populations of Cottus gobio across the three main drainage systems – Elbe, Danube and Odra in area of the Czech Republic where all three drainages are in close contact. The results of former studies in Germany and the fact that C. gobio is non-migratory, bottom-dwelling species led us to expect larger differences among populations from different drainage systems.

            The analysis showed larger differentiation between populations of Odra drainage system on the one side and Elbe and Danube systems on the other one. The mean value of genetic distances found out in our area between the populations of Elbe and Danube basins was lower than those between the same basins in Germany. Although the most different populations were those from Odra River basin, the differences (and thereby the divergence time calculated from genetic distances) were also smaller than I expected according to different geographic history of this area and according to hypothesis, that C. gobio has colonised this area via different (eastern) colonisation route and so has diverged earlier. Smaller differences could be explained by mixing populations from different drainages via stream captures in bordering areas in the evolutionary history. Different colonisation route could be the reason of larger differentiation of Odra basin populations but supposed secondary contact could lower the values to the found level.

This study was supported by the Grant Agency AS CR (S 504511) and by an internal grant of IAPG (ڎFG/00/13).  



Abstract and topic of my master thesis  


My study dealed with phylogeographic history of Cottus populations in the southern Europe with main focus on the perialpine area, Dinaric Mountains and rivers of the Northern Adriatic freshwater drainage. The aim of the study is to answer the questions of the highest European Mountains - the Alps - as a geographical barrier to dispersal of cold - adapted freshwater fish Cottus gobio. It should answer the question of origin of Northern Adriatic populations of Cottus, their relationship with Cottus from adjacent river basins and their taxonomic status as the area of our interest covers the distribution area of a doubtfull species Cottus ferrugineus.   


     The freshwater faunas of the Italian peninsula are isolated from the rest of Europe by the geographic barrier of the Alps and consequently have developed many endemic forms and contain few non-endemic species. However, some non-endemics may either represent recent invaders of the Adriatic basin or cryptic endemic species. To test these two hypotheses against each other, we studied the origin and phylogenetic relationships of bullheads, cold adapted freshwater .shes of the genus Cottus, from both sides of the Alps and Dinaric Mountains. From the Adriatic basin, Cottus ferrugineus (Heckel and Kner, 1858) was described as an endemic species, but the present analyses of sequences of the complete mitochondrial control region of 146 individuals from 43 localities showed no major di.erentiation between bullheads from both sides of the Alps. The very low diversi.cation between representatives across the Alps suggests active transfers of haplotypes across this geographic barrier from the glacial cycles up to recent times. The transfers are most likely based on stream capture, since the cold-adapted bullhead is able to colonise the highest stretches of the water courses. No other freshwater .sh in Europe is known to have experienced such an extensive gene .ow across the highest European Mountains. In contrast, the Dinaric Mountains seem to have been a much more e.ective barrier between the Danube and the Adriatics. Our data reject the hypothesis of C. ferrugineus as an endemic species in the whole Adriatic drainage.


Special thanks I owe to J. Bohlen, for his constant help throughout the whole study in all respects - collecting material, interpretation of data as well as a psychological support. On the next place, my thanks belong to J. Freyhof as to initiator of this study and author of its original idea. Next, I would like to express my thanks to G. Delmastro, J. Freyhof, L. Kalous, M. Kottelat, M. Mrakovcic, A. Nolte, H. Persat & J. Schöffmann for help in the field, for provision of samples or for help with obtaining the samples. Very helpful advises regarding the laboratory work and the data analyses came from I. Doadrio, C. Cunha, A. Marchodom, A. Nolte, A. Perdices & K-E. Witte. Earlier drafts of the manuscript improved much due to the critical comments of P. Koltík, M. Macholán, P. Rab  V. Slechta. 


 Šlechtová, V., J. Bohlen, J. Freyhof, H. Persat, G.B. Delmastro (in press): The Alps as barrier to dispersal in cold-adapted freshwater fishes? Phylogeographic history and taxonomic status of the bullhead in the Adriatic freshwater drainage. Mol.Phyl.Evol., 33: 225-239.




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