The organism trapped in a merciless evolutionary time loop has been identified. Who is it? (Watch the video)

Lake Mendota in Wisconsin undergoes transformations due to seasonal changes: it freezes over in winter and becomes overgrown with algae in summer. In a new study, scientists examined the lake and discovered an organism trapped in evolutionary loops due to cyclical shifts in climate, reports Science Alert.

The research was conducted by a team from the University of Texas at Austin. During the study, researchers analyzed 471 samples of lake microbes collected over two decades and then examined genetic changes within and between species over time.

Data revealed that thousands of bacterial species evolve over generations and then revert to nearly identical states as the seasons change. Since microbes typically live only a few days, this refers to genetic evolution spanning thousands of generations within a single year.

According to co-author of the study, marine scientist Brett Baker from the University of Texas at Austin, these cycles repeated year after year. Of the 2855 bacterial genomes studied, cyclical seasonal changes were observed in 80% of them. The researchers also note that their findings fundamentally alter our understanding of how microbial communities change over time. Furthermore, scientists believe that the new data will provide significant insights into microbial ecology and evolution in nature.

The analysis indicated that as environmental conditions changed, various bacterial strains thrived and eventually became dominant, overshadowing other strains as the seasons shifted. Approximately 20% of the studied species also exhibited a more stable pattern of genetic changes spanning decades.

This behavior was particularly noticeable in 2012 when the lake experienced a hotter and drier summer. The study authors observed a significant shift in the genes regulating nitrogen metabolism of bacteria during that time. This change is thought to have resulted from lower levels of nitrogen-producing algae.

The team also utilized a supercomputer, which significantly expedited their process. Scientists collected metagenomes from each water sample, allowing them to thoroughly analyze the DNA genetic sequences over time.

According to co-author of the study, microbiologist Robin Rover from the University of Texas, their findings suggest that ecology and evolution likely go hand in hand rather than acting independently. The study authors also emphasize that this is an important discovery, especially regarding the study of a warming Earth.

Understanding which bacterial strains will dominate helps scientists assess how much carbon lakes can absorb and how aquatic food chains may be affected by adaptations to warmer seasons. This knowledge is particularly crucial in the context of climate change, which is gradually shifting seasons and altering average temperatures while also causing extreme weather events.