Ecological and evolutionary constraints of prokaryotic microbial biodiversity in terrestrial and lake ecosystems of Svalbard, RiS 6206

The diversity of polar (cyano)bacteria has not been well explored until now. In contrast to vascular plants and animals, little is known about the biodiversity, biogeography and evolutionary history of prokaryotic microbial organisms. The traditional vi ew is that historical factors are of little relevance in shaping current communities as dispersal is rarely limiting, resulting in the bipolar/alpine distribution of most microbial taxa. However, current paradigms on microbial biogeography may be incorrec t as they are largely based on morphological identification criteria or studied using molecular markers with a low taxonomic resolution. More recent studies using high taxonomic resolution have shown that some microbial taxa appear to be restricted to cer tain Polar Regions. Previous results (in Antarctic polar regions) have shown that in each new sample studied, several new genotypes (based on 16S rRNA gene sequences) were found. Among these, many genotypes were recorded in only one sample, and some seem ed to have a biogeographic distribution limited to the areas in which they were found. Using a combination of next generation sequencing technologies and dedicated culture-based studies, it is now possible to assess the degree of biogeographical structur ing of microbial taxa possessing a variety of life cycle characteristics and dispersal capacities, and test earlier hypotheses about the evolution of bipolar distributions in microbes. Such studies are highly relevant for the rapidly changing Polar Region s and will provide an evolutionary context against which to assess climate-induced alterations.