Frequency/distribution of nucleotides/amino acids before selection
ram.samudrala at stanford.nojunkemail
Mon Nov 2 21:44:42 EST 1998
Donald Forsdyke <forsdyke at post.queensu.ca> wrote:
> Drs. Hickey and Lobry have both accepted Dr. Samudrala's premise
>that base composition changes "before selection kicks in".
The premise is that the amino acid composition is different in a gene
prior to selection (i.e., before selective pressures arise for the
protein encoded by the gene) and after selection [*]. I believe this
follows from the Neodarwinian theory of evolution. If the
compositions are identical what purpose would selection serve (I do
think that proteins in general are fairly well-clustered around their
average amino acid compositions)?
>How do we know when "selection" first "kicks in"?
That's related to my question. You can argue selection cannot be
present in a gene that isn't functional. But I think it is a
difficult question to answer, which is why I asked.
I thank Drs. Hickey and Lobry for their papers which I will look up.
* - The data for the latter is present in many text books.
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