The impact of differences in land use on the clonal structure and genotypic diversity of the salt marsh species Elymusathericus: A study based on Microsatellite markers

In recent years evidence has accumulated that certain plant species can rapidly adapt to drastic environmental changes (e.g. develop heavy metal tolerance). The ability for adaptation might enable some species to expand their distribution in a situation of rapid change, whereas evolutionary more conservative species might disappear. In 1972 different management forms (mowing, grazing) have been applied to certain abandoned areas of a salt marsh section on the Dutch Wadden Sea Island Schiermonnikoog. Mowing and grazing can be considered as drastic environmental change in the salt marsh ecosystem. We observed that Elymus athericus, an invasive clonal grass, exhibited large phenotypic differences between the different treatments. We hypothesised that different management regimes can change selection pressures on Elymus athericus when compared with the natural situation. As a consequence populations could have developed not only phenotypic differences between treatments but also differences in clonal and genetic structure. In this study we analysed clonal structure and genetic diversity between treatments with the help of five polymorphic Microsatellite markers. Differences in genotypic diversity were found between the management regimes. In the dense vegetation of the unmanaged areas clonal propagation was favoured. The highest genotypic diversity was found in the mown plots, where seedlings have the highest likelihood to recruit.