Short communication ANALYSIS OF MTDNA SEQUENCES OF EUROPEAN GRAYLING,

ABSTRACT. Nucleotide sequences of the partial mitochondrial DNA (mtDNA) control region and flanking tRNA Phe gene (a total of 150bp) were determined in eight specimens of European grayling, Thymallus thymallus, representing five rivers in southwestern Poland. Two haplotypes, A and B, were identified which differed from each other by two nucleotide substitutions. Haplotype A was detected in fish from two rivers, the Zadrna and Bóbr, whereas haplotype B was detected in fish from three others, the Widna, Biala Gluchoazka and Metuja. The different phylogenetic position of the mtDNA haplotypes observed in samples from rivers which are in close proximity may suggest genetic structuring of grayling populations in the region, but further sampling is required to test this hypothesis. Key words: D-LOOP, mtDNA VARIATION, EUROPEAN GRAYLING (THYMALLUS THYMALLUS) European grayling Thymallus thymallus is widely distributed across the continent. It occurs in two main regions; the majority of this species is found in northern Europe and a much smaller part is distributed throughout the western area, including Eng-land and Denmark. In Poland, the grayling is distributed mainly in the southern upland part of the country throughout the mountain regions in the basins of the Oder and Vistula rivers. A few other populations occur in northern Poland mainly due to stocking (Witkowski et al. 1984). Recent molecular-based phylogeographic studies on European grayling have shown rich and complex distribution of mtDNA variation which is difficult to explain in the light of simple zoogeographical generalizations (Koskinen et al. 2000, Weiss et al. 2002). However, there is growing appreciation of the fact that a significant amount of genetic variation remains to be uncovered among other populations, including those of T. thymallus in Poland. This communication reports the first observations of mtDNA variation among the grayling individuals inhabiting rivers in southwester