Bacteria make major evolutionary shift in the lab
Bacteria make major evolutionary shift in the lab
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.
Twenty years ago, evolutionary biologist Richard Lenski of Michigan State University in East Lansing, US, took a single Escherichia coli bacterium and used its descendants to found 12 laboratory populations.
The 12 have been growing ever since, gradually accumulating mutations and evolving for more than 44,000 generations, while Lenski watches what happens.
Profound change
Mostly, the patterns Lenski saw were similar in each separate population. All 12 evolved larger cells, for example, as well as faster growth rates on the glucose they were fed, and lower peak population densities.
But 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.
Jun 10, 2008 @ 07:03:10
Well, if the ability to process an entirely new form of “food” can’t be classified as an increase in information (or at least not a decrease) then I’m not sure what would.
However, it’s only a matter of seconds until creationists start the old line “it’s still just a bacterium though, it doesn’t even have wings”. Or “it’s not evolution, it’s just a different KIND”. If they haven’t started banging on with the same crap already yet.
Jun 10, 2008 @ 08:37:12
I think the scientists are missing the obvious: God decided they weren’t getting enough to eat, so it gave them the ability to eat more of their environment. Or, maybe the Devil gave them that ability so it would be reported as “news” and thus lead the faithful away from God because they’d now believe the lie called “Evilution”. Or, maybe God did it just to test the faith of his faithful. Just because he’s all-knowing doesn’t mean he knows what his faithful are going to do just because he does know what they’re going to do.
Or, perhaps it’s the simpler, more rational reason like the article says. :)