| Summary: | 14th International Conference on Harmful Algae, 1-5 November 2010, Creta, Greece Genetic differences among clones and populations of HAB species may have a major effect on their phenotypes, such as toxicity, growth rates, and salinity tolerance. Moreover, genetic differentiation and divergence among populations may lead to reduced gene flow and eventually speciation. Here, we investigated possible genetic divergence due to either local adaptation and/or geographic isolation. As a model system, we used marine dinoflagellates in recently formed Antarctic saline lakes. One species, Scrippsiella hangoei forms blooms in the Baltic Sea, while the other, Polarella glacialis is common in both polar seas. Clonal strains of the two different species were isolated from lakes of different salinities. To study local adaptation, we tested salinity tolerance in marine and limnic strains. The genetic difference among the strains was determined using a DNA fingerprinting technique (AFLP). The AFLP analyses indicated that the lake strains were more closely related to each other than to the marine strains. The salinity tolerance experiments showed that the limnic strains had a wider salinity tolerance than the marine strains, and that the limnic strains were adapted to the salinity ranges of their lake of origin. We tentatively suggest that the limnic populations have undergone local adaptation and may be genetically isolated from the marine populations Peer reviewed
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