That is a good question.
Concerted evolution (various mechanisms) keeps the copies the same as each other. The copy number changes over time and no one copy in one species is considered the orthologue of a copy in another except when the copy number is small and individual copies are identified by position.
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).
Des
"Jason S" <jas2339 at yahoo.com> wrote in message news:mailman.1073.1148420085.16885.mol-evol at net.bio.net...
Hi there,
Here's a newbie question: if there are hundreds of copies of ribosomal genes in a genome, how can we know which copy we are working on? and how can we be sure that they are orthologous among species?
With best regards,
Jason
jas2339 at yahoo.com
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