Genetics as it applies to evolution, molecular biology, and medical aspects.
6 posts • Page 1 of 1
A question for geneticists -
How essential is it that a gene or other section of DNA that performs a useful function is at a particular locus? I ask, because I am discussing endogenous retroviruses (ERVs) with an evolution-denier, who says that the ERVs that are apparently orthologous in, say, chimps and humans, are there because they infected both species independently and were fixed by positive selection pressure. IOW, selection pressure acted as a 'sieve', retaining only the ERVs that served an adaptive function. (We cannot say that not all ERVs serve an adaptive function - it may be that we just haven't discovered what adaptive functions they serve.) The reasoning fails if the adaptive functions do not depend on their exact loci.
The issue is whether there's an adaptive function. It seems like the adaptive function is non-expression, which might be affected by location, or might not. If the ERVs are in similar locations, that would imply that they entered the system in a shared ancestor...
I don't really understand your reasoning. However, retroviruses are the major players and drivers of evolution. When they insert into host genome, they can alter host genes located at and around the insertion point - they can disrupt genes, activate genes, alter gene expression.
When they said that the reasoning fails if location doesn't matter, I think they were implying that these 'orthologous' (homologous) sequences are at the same loci in chimps and humans. The idea is that, with all the possible locations for this sequence, it is improbable that it would wind up in the same location within each species. If that is indeed the argument, I would suggest the possibility that similar location is due to the way the virus inserts its genetic material.
If the argument is that ERVs are in corresponding locations because they need to be to fulfil a design purpose, then the argument fails if functional ERV genes do not need to be in specific locations in order to perform their functions. Unless we are talking about LTR promoters of native genes, this does seem to be the case.
Re. locus targeting, see http://erv-faq-for-creationists.wikispa ... ng+ERVs%3F
6 posts • Page 1 of 1
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