Re: Rapid Lizard Evo

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

> how many organisms don't benefit from recombination?

Bdelloid rotifers... (Prominent in last week's Nature.)

> Surely genes can
> 'cross over' (nothing to do with John Edwards) during asexual cell 
> division just as
> much as during meiosis?

They don't, though. In eukaryotes that only happens during DNA repair and in 
meiosis, when special enzymes for making and repairing double-strand breaks 
are switched on -- and some do it only in meiosis (there are no knock-out 
flies because "*Drosophila*" doesn't do recombination outside of meiosis; 
people have to resort to knock-down flies).

> I suppose it depends on how you define 'random mutation'. I tend to 
> restrict
> it's use to random changes in gene structure due to outside influences
> (radiation, mutagenic chemicals, etc), whereby genetic damage is inflicted
> that isn't completely repaired by the cell.

Also mistakes in copying, and insertion of transposable stuff and virus 
genomes.

> I suppose some people might use
> the term more broadly to encompass any process that alters a gene sequence
> (which would include recombination).

Recombination is directed mutagenesis: the site at which the mutation 
happens is not random.