Genetic differentiation of European grayling populations across the Main, Danube and Elbe drainages in Bavaria

Analysis of mitochondrial (ND-1/3/4 genes) and nuclear (GH-I gene, four mic rosatellite loci) DNA markers of European grayling Thymallus thymallus popu lations identified strong genetic differentiation between the Rhine/Main, E lbe and Danube drainages in Bavaria, as a result of both present processes and past history. The Danube and the Main-Elbe group diverged about five ti mes earlier than the populations of Main and Elbe. These data suggest that exchange and transfer of grayling stocking material between these drainages should be avoided, to maintain the genetic diversity and integrity of popu lations. (C) 2001 The Fisheries Society of the British Isles.