Re: Mice given bat-like forelimbs through gene switch

[David Marjanovic <david.marjanovic@gmx.at>]

> Retroviruses are be able to combine the DNA of different species. In fact,
> endogenous retrovirus sequences have become a permanent part of the human
> genome. Up to 8% of our genes once belonged to other species.
> http://en.wikipedia.org/wiki/Endogenous_retrovirus

If you count all the retrotransposons and the formerly transposable elements 
(like LINEs and SINEs) as retrovirus material, over half (53 % or so) of our 
genome consists of retrovirus corpses in various stages of decay...

> Bacteria are able to exchange gene sequences not just between different 
> members
> of the same species, but between different bacterial species.

Not only. Don't you remember the famous photo of a hamster cell and two 
bacterial cells doing it?

That must be why vertebrates share some genes with bacteria but with nothing 
else... and why the bacterium *Mycoplasma genitalium* contains genes for the 
synthesis of cholesterol, something otherwise limited to eukaryotes... never 
mind all the genes spread across (hyper)thermophilic bacteria and archaea 
alike...

In fact, what is a bacterial "species" or an archaeal "one"? Most species 
concepts are simply not applicable, and the rest needs arbitrary cutoff 
points (% similarity in genome sequence, % similarity in AT content). It 
would make a lot more sense to just talk about clades.