Researchers at Michigan State University have just revealed that evolution is as easy as 1-2-3. Their goal was to observe how fast growing E.coli could evolve to digest citrate along with their normal diet of glucose. E.coli bacteria is unable to digest the protein citrate, but through natural selection, they evolved right before the researchers’ eyes to be able to go to town on their new delicacy.
Richard Lenski, one of the lead researchers, explained that,
“We first saw the citrate-using bacteria around 33,000 generations, but Zack was able to show that some of the important mutations had already occurred before then by replaying evolution from different intermediate stages. He showed you could re-evolve the citrate-eaters, but only after some of the other pieces of the puzzle were in place.”
Three steps are required for the mutation to take place. In the first step, potentiation, the E. coli developed two minor mutations that prepared them to evolve further. During actualization, the second step, the bacteria began taking tiny bites of the citrate, seemingly out of curiosity. In the final step, refinement, major mutations occurred that allowed the E.coli to gluttonously eat the citrate. This ability quickly became dominant in the colonies of bacteria.
Researchers were understandably excited as they were able to witness the mutation with unprecedented clarity Lenski states that, in regards to the actualization stage,
“It wasn’t a typical mutation at all, where just one base-pair, one letter, in the genome is changed,” he said. “Instead, part of the genome was copied so that two chunks of DNA were stitched together in a new way. One chunk encoded a protein to get citrate into the cell, and the other chunk caused that protein to be expressed.”
Fun fact: many people believe, as a way to disprove evolution, that dinosaur fossils are simply an attempt by God to test our faith.
Fun fact: the article you just read.
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