MSU Research History: Evolutionary Study in Petri Dish
1988 – Richard Lenski, John A. Hannah Distinguished Professor of microbial ecology, begins an experiment with 12 populations of E. coli—all started from the same ancestral strain and all living in identical environments—to see how similarly or differently they would evolve.
Initially, Lenski wanted to keep the experiment going for at least a year and about 2,000 bacterial generations, maybe longer. After twenty-five years, the experiment was still going strong and was up to more than 58,000 generations.
What makes Lenski’s work unusual is that most evolutionary biologists study evolution by examining fossils or by comparing different species. His team studies evolution by doing experiments where they can watch evolution in action. That means that they have to study fast-reproducing organisms, like bacteria, in order to observe lots of generations.
The plate on the left contains about equal numbers of colonies of two different bacteria. After the bacteria compete and evolve, the lighter ones have taken the lead in the plate on the right.
Photo: Courtesy of Michael Wiser