How Organisms Evolve New Functions: Evolution Is as Complicated as ...

Genomic analysis of 56,000 generations of E Coli let researchers followed the molecular events as a new function evolved.

A team of researchers at Michigan State University has documented the step-by-step process in which organisms evolve new functions.

Blount and his teammates analyzed 29 genomes from different generations to find the mutational pieces of the puzzle. They uncovered a three-step process in which the bacteria developed this new ability.

The first stage was potentiation, when the E. coli accumulated at least two mutations that set the stage for later events. The second step, actualization, is when the bacteria first began eating citrate, but only just barely nibbling at it. The final stage, refinement, involved mutations that greatly improved the initially weak function. This allowed the citrate eaters to wolf down their new food source and to become dominant in the population.

Zachary Blount, the postdoc who led the investigation, poses with petri dishes from the study.