Phylogeographic patterns of isolation within and among geothermal habitats

Tin, Sara

A large number of studies have revealed a great abundance of bacteria in geothermal areas around the globe. However, we understand very little about the evolutionary processes that generate this fantastic diversity. In this study, we used culture independent methods to explore bacterial diversity of geothermal flowing spring source waters and test specific hypotheses of geographical isolationi. As expected, source waters revealed a greater diversity than downstream sediments within the same flowing stream. In addition, considerable overlap in diversity of microbial communities both within and between springs was uncovered. However, there was strong evidence for geographic isolation within particular phylogenetic groups such [as] Aquificales and Thermus-Deinococcus, though, these were not strict monophyletic groups based on geography, suggesting considerable movement was taking place between springs. These methods also discovered a remarkably diverse new group of bacterial sequences with no cultured representatives that may be a new division. These sequences were highly abundant in 2 springs, separated by 3 km in Yellowstone National Park, in 2005, but were not seen in either spring before or after that date.