Understanding how and why diversification occurs is important for understanding why there are so many species on Earth. A new study found that similar, or even identical, mutations can occur during diversification in completely separate populations of E. coli evolving over more than 1,000 generations.

The new study involved 3 different populations of bacteria. At the start of the experiment, each population consisted of generalists competing for two different sources of dietary carbon (glucose and acetate), but after 1,200 generations they had evolved into two coexisting types each with a specialized physiology adapted to one of the foods. The researchers were able to sequence the genomes of populations of bacteria frozen at 16 different points during their evolution, and discovered a surprising amount of similarity in their evolution.

"Not only did similar genetic changes occur, but the temporal sequence in which the changes occur over evolutionary time was also similar between the different evolving populations. This 'parallelism' implies that diversification is a deterministic process driven by natural selection," said co-author and University of British Columbia zoologist Prof. Michael Doebeli.

Is Evolution Now Predictable?