The genus Asplenium in Europe comprises some 50 taxa: half of these are diploid while the other half are polyploids derived from the diploids. All Aspleniums in Europe are (small) rock ferns with high substrate specificity. Today, most of mainland Europe, Scandinavia and the British Isles has been colonised by polyploid Asplenium species, while the diploids that gave rise to these polyploids are distributed (and confined, more or less) around the Mediterranean Basin. In our research we investigate genetic variation and population distribution in polyploid complexes in Asplenium to locate centres of genetic diversity. The partitioning of genetic variation and discontinuities in the distribution of breeding systems in diploid and tetraploid taxa can help to locate the areas in Europe that are refugia for biodiversity, and are likely to have been so since the beginning of the Pleistocene during the consecutive cold and warm periods in Europe.

Key words: allozymes, Asplenium, breeding systems, genetic diversity, glacial refugia