Isozyme analysis as a test for the relict status of Mediterranean bryophytes. I. The status of Bartramia stricta Brid. in the Mosel valley (Germany)

Plant and animal species with Mediterranean ranges and disjunct occurrences in Central Europe on exposed habitats are usually interpreted as relicts o f a postglacial warm climatic period (6000-7800 years BP). Isozyme analysis of different populations of Bartramia stricta Brid. from southern France a nd the Mosel valley area in Germany revealed that the German populations st udied are identical to one of two populations from southern France. This co uld be explained by the fact that only one population from southern France was able to extend its range to the north and to survive there. It could al so mean that the disjunct occurrence in Central Europe is a consequence of later spore dispersal from southern France and Bartramia stricta would not be a relict species in Germany. (C) 2000 Adac/Editions scientifiques et med icales Elsevier SAS.