Re: Question: How to recognize mutations

On Apr 20, 5:16 pm, r norman <r_s_norman@xxxxxxxxxxxx> wrote:
On 20 Apr 2007 07:01:33 -0700, ErikW <bryoph...@xxxxxxxxxxx> wrote:

On Apr 20, 3:48 pm, Bloopenblop...@xxxxxxxx wrote:

snip

So for example, there's the famous story about peppered moths adapting
to the industrial revolution. Was this really the result of mutations,
or could it have been recombination of existing alleles? And how do we
know?

Ask yourself why you call it alleles.

There is a point to the question. Something like industrial melanism
could easily have resulted with absolutely no mutation or alteration
in the DNA whatsoever. It could be simply a change in the frequency
of existing alleles, or a change in the frequency of particular allele
combinations. A "novel" phenotypic feature can easily result from a
novel combination of existing alleles.

As you already know, existing alleles are also the result of a
mutation one way or another. Witohut a change in the genome s. lat.,
no change in the phenotype. Remember we're not talking about
populations but individuals here. As you already know.

Transposons and gene
transference are, indeed, forms of mutation but even those do not
result from the development of "new genetic information" but merely
from the rearrangement of already existing sequences.

To me this just illustrates why "genetic information" as a concept has
rather limited utility for me.


Although I strongly suspect an ulterior motive in the question, it
still is a valid molecular biological point. The easiest way now to
detect "novel genetic information" (i.e. the sort of mutation I
believe the questioner is asking about) is through sequence analysis,
finding a DNA sequence that is not present in other members of the
species.

Often, or perhaps even usually, especially for phenotypic evolution,
natural selection has been described as acting on existing variation
as opposed to having to wait for mutations. I think most hold this
view for phenotypic evolution even though molecular evolution seem to
be mutation driven.

ErikW

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