Posted: Jun 20, 2012 11:02 am
GenesForLife wrote:While cellular stress does seem to increase the accumulation of CNV's, there is no arbitrary trend in favour of beneficial CNVs, for instance.
This is the key phrase here I think. If one were to postulate that CNV's were somehow being intentionally guided into place, because the organism in question "needs" them in order to adapt to some environmental stress, you'd expect them to only or maybe just mostly show up in areas where they positively affect the fitness of the organism.
You could test this claim with an experiment along these lines: Have a population of sufficiently complex but fast-growing single-celled eucaryotes, like yeast, grow under stable conditions in some set medium for an extended period and record the areas of the genome where CNV's show up and how often/likely they are. Now change the growth-medium to one that has a high concentraton of some nutrient which, if the organism had more copies of a relevant enzyme-producing gene, would increase it's fitness, and record the frequency and locations of CNV's again.
If CNV's were being guided for the benefit of the organism, you'd expect an increased frequency of CNV's in the enzyme-coding loci. But if evolution, as it is normally understood by the scientific community, is true, then you'd expect a random distribution of CNV's irrespective of loci. Only the frequency should go up, if at all.