A rather amazing thing has happened in the lab of Richard Lenski that advances our understanding of evolution while simultaneously discrediting many of the creationist/ID arguments against evolution based on probability and irreducible complexity. Take a look at The Loom blog for a great synopsis.

Lenski has been maintaining E. coli in a glucose limited state since 1988 to observe there evolution. He has twelve strains, all originating from one cell, which have been kept in continuous culture for 20 years. Now, one of the strains has spontaneously evolved a means to utilize citrate as its primary carbon source, something E. coli are unable to do.

This might not be such big news if it weren't so unlikely to have happened. The original strains were retested on citrate and were unable to survive on it. Even later strains held a probability of producing this mutation of only 1 in a trillion.

Furthermore, this inability to utilize citrate has been a defining feature of E. coli as a species. It has only been seen in E. coli which absorbed DNA plasmids from other bacteria which coded for the transport molecule. E. coli do not have genetic coding that would allow trasnport of this large molecule across the cell membrane.

Anyone who has taken cell biology classes knows that membrane transport proteins are very complex. To suddenly evolve one that works in this way, even if it uses a previous gene and mutates its form, is exceedingly difficult. To prove that this level of evolution can occur in only 20 years is a BIG deal.

Still, IDiots and creationists will most likely dismiss this as "micro-evolution" since the bacteria did not suddenly evolve into a multicellular organism. Oh, well. They can argue their case, but they will find that this paper completely irradicates most of the arguments for irreducible complexity that they trumpet. It also completely demolishes the idea that vanishly small probabilities in and of themselves are enough to discount evolution as a process by which mutation can cause significant change. Of course these arguments were already discredited but this blows them completely out of the water.

Bacterial taxonomy does not comply well with the traditional idea of species since bacteria transfer genes asexually and are therefore clones of each other, not offspring. Also, they are able to transfer partial DNA between species as plasmids, rings of partial DNA. This makes it incredibly hard to determine when a population is unable to breed, since often no breeding is involved in their reproduction.

If bacteria were not so difficult to classify it would be a no-brainer to say that a new species was evolved. As it is, this is not that clean but is quite close. It takes the creationist argument that we have never seen speciation in a controlled lab setting and puts it on it's heels.

This is incredibly exciting research and I can't wait to here more from this lab.