Bacteria make major evolutionary shift in the lab

New Scientist ^

[mnehring]

A major evolutionary innovation has unfurled right in front of researchers' eyes. It's the first time evolution has been caught in the act of making such a rare and complex new trait.

And because the species in question is a bacterium, scientists have been able to replay history to show how this evolutionary novelty grew from the accumulation of unpredictable, chance events.

[allmendream]

Any change in allele frequency in a population is evolution by definition.

[allmendream]

Moreover this variability, where did it come from?

The e.coli bacteria cannot break down citric acid. The evolved strain can break down citric acid. This was not an intraspecies variability that was selected for or against - it was an entire trait that was not present but now is (due no doubt to the mutation of a few enzymes that make them now able to break down citric acid when previously they could not).