DETROIT – Scientists now have physical proof of how species evolve and the fittest survive, after a 21-year study in which they documented the evolution of single-celled E. coli bacteria over 40,000 generations.
Lenski’s team periodically froze bacteria for later study, and technology has since developed to allow complete genetic sequencing. By the 20,000-generation midpoint, researchers discovered 45 mutations among surviving cells in the bottled bacteria.
Those mutations, according to
The results “beautifully emphasise the succession of mutational events that allowed these organisms to climb toward higher and higher efficiency in their environment”, noted
Lenski’s long-running experiment itself is uniquely suited to answer some critical questions — such as whether rates of change in a bacteria’s genome move in tandem with its fitness to survive.
A mutation involved in DNA metabolism arose around generation 26,000, causing the mutation rate everywhere else in the genome to increase dramatically.
The number of mutations jumped to 653 by generation 40,000, but researchers surmise that most of the late-evolving mutations were not helpful to the bacteria, said an MSU release.
“So what we learn here can help us better understand the course of these diseases.”
The paper involved collaboration with scientists from South Korea as well as
The findings were published in Nature.