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Šedivá, A., A. Apostolou, J. Kohout, J. Bohlen

Molecular phylogenetic analyses of the loach Oxinoemacheilus bureschi reveal postglacial range extensions across the Balkans

Journal of Fish Biology 76: 357-368.

The rivers on the Balkan Peninsula can be separated into different ichthyofaunistic areas with different endemic fish species. Especially the river Vardar contains a high number of endemics, indicating its complete and long-term isolation from neighbouring river systems. One of the few species shared with other rivers is the loach species Oxynoemacheilus bureschi (Drensky). In this study, the genetic analyses of 175 individuals ofO. bureschi from 17 sites, covering the whole distribution area of the species, the drainage areas of Vardar (= Axios), Struma (= Strymon), Mesta (= Nestos) and Danube, were performed using one mitochondrial and one nuclear marker. The genetic differentiation among populations was in general low, shared haplotypes were very common and occurred even between distant localities and different river systems. This points to a high degree of gene flow among populations and rejects the hypothesis that the population in river Vardar represents a relict from early colonisation of the Balkan Peninsula. In contrast, it suggests that populations in the Vardar River as well as in the Danube R. are of recent origin, and a human-mediated introduction cannot be excluded. On the other hand, the populations from the Aggitis R., a left tributary of the lower Struma R., were clearly separated from the rest of the species and represent a long-term isolated lineage. Demographic analyses suggest a recent population expansion for O. bureschi, in which the Aggitis R. was not involved. Because of the highest genetic diversity, the Struma R. basin is considered to be the probable centre of dispersal.