Evolution witnessed in lab setting

[FlaSoxxJim]

A landmark research finding was published yesterday in the Proceedings of the National Academy of Sciences. Scientists working out of the lab of Richard Lenski of Michigan State University published a paper called "Historical contingency and the evolution of a key innovation in an experimental population of Escherichia coli" that is being described by NewScientist as "the first time evolution has been caught in the act of making such a rare and complex new trait."

 

In a nutshell, Lenski has been growing 12 laboratory populations of E. coli in the lab for 20 years, all of them derived from a single bacterium. The goal was to allow random mutations within each population to accumulate and to see if/how those accumulated mutations resulted in divergent populations over time.

 

This has gone on for 44,000 generations, which is roughly the equivalent of a million years in terms of human generation time. Every 500 generations, Kenski would freeze a sample from each population so if interesting difference did arise he would be able to go back and tease out the whens and hows.

 

Now, patience and persistence have paid off. From the NewScientist piece:

 

sometime around the 31,500th generation, something dramatic happened in just one of the populations – the bacteria suddenly acquired the ability to metabolise citrate, a second nutrient in their culture medium that E. coli normally cannot use.

 

Indeed, the inability to use citrate is one of the traits by which bacteriologists distinguish E. coli from other species. The citrate-using mutants increased in population size and diversity.

 

"It's the most profound change we have seen during the experiment. This was clearly something quite different for them, and it's outside what was normally considered the bounds of E. coli as a species, which makes it especially interesting," says Lenski.

 

. . .

 

The replays showed that even when he looked at trillions of cells, only the original population re-evolved Cit+ – and only when he started the replay from generation 20,000 or greater. Something, he concluded, must have happened around generation 20,000 that laid the groundwork for Cit+ to later evolve.

 

Lenski and his colleagues are now working to identify just what that earlier change was, and how it made the Cit+ mutation possible more than 10,000 generations later.

 

Good stuff!

[BigSqwert]

Wow. That really is awesome!

[Reddy]

proof.

 

/end debate.

[mr_genius]

 

thats a great experiment, i love hearing about stuff like this