[Molecular-evolution] Re: ribosomal genes

Des Higgins dazzhiggins at hotmail.com
Tue May 30 06:12:56 EST 2006

"Peter Ellis" <pjie2 at cam.ac.uk> wrote in message 
news:mailman.13.1148958920.18505.mol-evol at net.bio.net...
>> "Des Higgins" <dazzhiggins at hotmail.com> wrote:
>>  The possible mechanisms that allow concerted evolution include unequal 
>> crossing over
>>  (you have tandem repeats that match up incorrectly at meiosis; these 
>> swap between
>>  chromosomes and some are gained and some lost; this repeated sampling 
>> creates
>>  uniformity over time) and gene conversion (transcript of one gene 
>> "corrects" the sequence
>>  of another).
> And how exact are these?  Any idea what percentage sequence variance, if 
> any, would you expect in the ribosomal sequences within a single 
> individual?

I do not have any exact data on this.  The textbooks say that variation 
between copies is minimal or zero.
It may depend on the species.  Species with just a few copies (e.g. 
bacteria) may have significant variation between copies (just a guess). 
Plasmodium certainly has variation between the small number (4-8 or so) of 
rRNA genes.  Humans and fungi can have hundereds opf copies in tandem arrays 
and if I had to guess, I would say they were mainly identical copies but 
that is a guess.

> Peter

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