Proc. Natl Acad. Sci. USA doi:10.1073/pnas.0905369107 (2010)

On the sea floor 15 kilometres west of the Mid-Atlantic Ridge lies the Lost City Hydrothermal Field, a collection of deep-water hydrothermal vents that has been active for at least 30,000 years.

William Brazelton of the University of Washington in Seattle and his colleagues analysed the bacteria and archaea that live in the vents' chimneys (pictured). They obtained more than 200,000 DNA sequences for a specific region and correlated these with the age of the organisms' habitats over a 1,200-year period. They found that sequences that occur rarely in young chimneys are more abundant in older chimneys.

The researchers suggest that over the many chimney life cycles that create reccurring environmental conditions, selection has resulted in many closely related species that are pre-adapted to specific conditions.