Some Bacteria Evolve Like Clockwork With the Seasons

January 3, 2025 • by Marc Airhart

The longest natural metagenome time series ever collected reveals a startling evolutionary pattern on repeat.

A lake at sunset with reeds poking up through the water

The team analyzed genetic material from microbes in a one-of-a-kind archive of water samples collected over 20 years from Lake Mendota in Wisconsin. Photo credit: Robin Rohwer/University of Texas at Austin.


Most species of bacteria in Lake Mendota rapidly evolved with the change of seasons, returning to a similar state every year, for 20 years. The blue dots represent how much individual species within the genus Nanopelagicus changed genetically over time. The black line represents a 6-month moving average. Credit: University of Texas at Austin.

A woman stands on a small boat holding a clear plastic tube hanging down into the silvery water

Robin Rohwer collects water samples on Lake Mendota in summer 2015. Credit: Robin Rohwer/University of Texas at Austin

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