Genome analysis and its aid in understanding evolution

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Genome analysis and its aid in understanding evolution

Post by donna_by_nature » Sun Jan 08, 2006 7:54 pm

Nowadays, there are many complete genomic sequences available for bacteria, allowing comparison between them and thus allowing the evolution of bacteria to be understood i.e/ the creation of taxonomic groups and a phylegeneic tree

However, as bacteria are continually exchanging genes, plasmids or entire chromosomes (by conjugation, transformation etc), is the correct phylogenic tree or taxonomy available through genomic analysis?

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Post by MrMistery » Mon Jan 09, 2006 7:42 pm

Bacteria can exchange entire chromosoms?

PS: Patrik will answer. He knows a thing or two about the evolution of bacteria
"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter

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Post by canalon » Mon Jan 09, 2006 8:25 pm

Back from 2 weeks of holiday I com with my 2 (canadian) cents ;)

First however much complte genome sequences there are they are scarcely a drop of water in the ocean compared to the number of bacterial species, not even talking about diversity in one species (Compare K12 and O157:H7 genome, 2 E. coli, 20% more genome in o157:H7). So we are far from having enough data to build a significant tree.
But the point you raise about what is usually reffered to as horizontal transfer is not a recent one and that is why phylogeneies are more interested in the housekeeping genes than in the other genes, probably less stable.

And this just point out how difficult it is to define what is indeed a bacterial species. And so much for the "real tree of life".

In fact there is a lot more to say about horizontal transfer and phylogeny, but I think I do not feel like writing a complete review on the subject. I have a few references that I will try to dig oout from my stacks of papers but, please be patient ;)

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

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