Scientists discover bacteria trapped in 'infinite evolutionary time loop'
The researchers found that the genetic characteristics of bacteria found in lakes that experience dramatic seasonal changes, such as being frozen over in winter and covered in algae in summer, are reset and restored to their original state each year.
Two decades of bacterial ecology and evolution in a freshwater lake | Nature Microbiology
Some Bacteria Evolve Like Clockwork With the Seasons - UT News
https://news.utexas.edu/2025/01/03/some-bacteria-evolve-like-clockwork-with-the-seasons/
Scientists Discover Bacteria Trapped in Endless Evolutionary Time Loop : ScienceAlert
https://www.sciencealert.com/scientists-discover-bacteria-trapped-in-endless-evolutionary-time-loop
Lake Mendota in Wisconsin, USA, experiences dramatic seasonal changes in its environment, with the lake surface covered in ice in winter and algae thriving in summer. Several types of bacteria live in Lake Mendota, but even the same type of bacteria has different adaptable conditions depending on the strain, with some active in summer and others active in winter, showing various characteristics.
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Robin Lower and her colleagues at the University of Texas at Austin studied 471 water samples taken from Lake Mendota over a 20-year period to see what genetic traits each bacterium acquired over time.
As a result, it was found that most of the bacterial species living in Lake Mendota have undergone rapid evolution over the course of a year. Because individual bacteria only have a lifespan of a few days, the speed of evolution is so rapid that thousands of generations have evolved over the course of a year, but when the seasons change, they return to almost the same state as they were a year ago.
'The genetic mutations waxed and waned over generations and then waned again over the course of the seasons, like a video being played in reverse,' Lower and his colleagues wrote.
The genetic changes were particularly evident in 2012, a hotter and drier than average summer when less water flowed into the lake, potentially reducing the amount of nitrogen-producing algae, leading to significant changes in the genes that control nitrogen metabolism in bacteria.
According to Lower and his colleagues, the 2,855 bacterial species studied evolved in response to their surrounding environments, with 20 percent showing persistent genetic changes over decades, while the remaining 80 percent reverted to a nearly identical genetic state each year.
'This work is a game changer in our understanding of how microbes change over time,' said Brett Baker, a marine scientist and co-author of the study. The study required massive computing power, and it was expected to take 34 years to analyze using a laptop, but it was completed in just a few months using a supercomputer at the Texas Advanced Computing Center.
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