Genetic variation in zinc-tolerant populations of Glyceria fluitans

Amplified fragment length polymorphism (AFLP) was used to conduct a study of the genetic diversity of zinc-tolerant populations of Glyceria fluitans from 10 sites from across Europe. Six different primer combinations were used on five to nine plants from each of the 10 sites to generate a total of 796 bands, of which 670 were polymorphic. These data were then used to calculate a dendrogram by agglomerative clustering using the unweighed pair group method with average linkage (UPGMA). The dendrogram contained two distinct clusters, with little overlap between populations. Genetic diversity between populations of G. fluitans did not always correlate with geographical distances, for example, plants from the Navan population from Ireland were more genetically similar to populations from Poland than other populations from Ireland. In other instances, geographical origin was significant, for example, all Polish populations were genetically similar to each other. Populations from two English sites only 160 km apart, showed such a high degree of genetic diversity that they were placed in different clusters in the dendrogram. They were more closely related to Irish and Polish populations than to each other. Plants from different zinc-contaminated sites were found not to cluster together. The conclusion was that the cluster groupings were not related to exposure to zinc at the sites of origin, and that the drive to generate distinct metal-tolerant populations may not occur in this species due to the existence of a constitutive tolerance to metals.