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Journal of Botany
Volume 2010 (2010), Article ID 596542, 11 pages
Research Article

Heavy Metal Pollution, Selection, and Genome Size: The Species of the Žerjav Study Revisited with Flow Cytometry

1Department of Systematic and Evolutionary Botany, University of Vienna, Rennweg 14, 1030 Vienna, Austria
2Core Unit for Medical Statistics and Informatics, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
3Department of Biogeography and Botanical Garden, University of Vienna, Rennweg 14, 1030 Vienna, Austria

Received 2 March 2010; Accepted 29 April 2010

Academic Editor: Jaroslav Doležel

Copyright © 2010 Eva M. Temsch et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The Death Valley at Žerjav in northern Slovenia exhibits a gradient of heavy metal pollution in the soil with severe consequences for species richness and composition along this gradient. Recently, a progressive loss of large-genome species in parallel with increasing concentrations of heavy metals has been shown. Here, we have measured the genome size of a near-complete sample of these species with flow cytometry and analysed the correlation of heavy metal pollution with the C- and Cx-values assigned to the test plots. The method of probability analysis was a hypergeometric distribution method. We confirm, on a different methodological basis than previously, that along the pollution gradient, species with high C- and Cx-values are increasingly underrepresented. This lends support to the “large genome constraint hypothesis”, predicting that plants with large genomes are at a disadvantage under all aspects of evolution, ecology, and phenotype, because junk DNA imposes a load to the organism.