Re: Felsenstein and reproductive excess
- From: "Perplexed in Peoria" <jimmenegay@xxxxxxxxxxxxx>
- Date: Mon, 13 Jun 2005 13:48:13 -0400 (EDT)
"Walter ReMine" <science@xxxxxxxx> wrote in message news:d8j3oi$2v9l$1@xxxxxxxxxxxxxxxxxxxxxx
> Perplexed in Peoria (Jun 12, 2:23 am):
>
> > Walter ReMine wrote:
> >> I presume you're referring to Felsenstein's other
> >> thread, and his highly artificial "model" where neutral
> >> mutations *occur*. In what conceivable sense might a
> >> mutation be called a "substitution"? That is your word
> >> here, not Felsenstein's.
> >
> > Well, what do you know? Here I was all ready to
> > deny you any credit for answering questions in
> > this posting. But you HAVE answered one - even
> > if indirectly. ReMine does NOT include mutation
> > in "substitution by reproductive means". Get that,
> > Joe?
>
> You're jumping to conclusions.
Typical! First he complains that I don't give him enough credit
for answering questions. Then he turns around and denies having
answered one.
> The issue here is not what I think. [snip]
The issue where? The issue ***I*** was exploring was precisely
"what you think". I was trying determine exactly what ***you***
mean in your often repeated refrain ending with the words
"NO EXCEPTIONS". Admittedly, you may have a different agenda
here. But you have offered no rationale as to why your agenda
should be the controlling one. You simply keep claiming
that your agenda is the only true agenda.
> So back
> up, and make a *reasonable* attempt to understand your own notion of
> "substitution" -- In what conceivable sense is a mutation a
> "substitution"? You don't need me to answer that for you.
Alright Walter, I will play your game.
To me, the base meaning of "substitution" has to be the replacement
of one allele (fixed in a population) with another (fixed in a
population). But in the current context (cost of substitution)
we all recognize that substitution is a process which takes place
over time. Because we expect that the "cost" will be "paid on the
installment plan" and that we will also "take delivery" incrementally
over the same period, it seems useful to have a concept of a
"partial substitution" - which is simply a change in allele frequency
or allele population from one generation to the next.
So, using this terminology, is a mutation a substitution? Clearly, it
is a partial substitution. In fact, it is required as the first
partial substitution in any scenario in which a novel allele becomes
fixed by either drift or selection. But is it a complete substitution?
Of course not (with one exception, see below). Can we create a
complete substitution out of repeated mutations? Almost certainly not.
There is only one (admittedly artificial) scenario in which a mutation
constitutes a substitution. This is when you have a haploid population
with a population size of 1 and a reproductive excess of zero. In
this case, mutation accomplishes the complete substitution (which takes
place in a single generation).
Incidentally, Walter, if you look at Felsenstein's "other thread", you
will see that I made exactly this point. Assuming that Felsenstein's
purpose was to clarify whether you include mutation as a mechanism of
"substitution by reproductive means", I suggested that he should simplify
his model by setting the population size to 1.
Satisfied Walter?
Now lets play a round of MY game!
[snip]
> > ... that means that ReMine must construe
> > "reproductive excess" as an attribute of haplotypes.
>
> Well, ah, not exactly. You're being needlessly fancy. Reproductive
> excess is a very simple concept. Keep it simple. It's not really about
> genetics, but even simpler than that. You don't need the notion of
> "haplotypes" in order to understand reproductive excess. Rather, you
> need a simpler (and only slightly more abstract) notion of reproductive
> excess.
>
> > Do I have this right, Walter?
>
> Close enough for now.
Here are the rules of my game. Very simple. You stop being coy and you
tell me what that "simpler (and only slightly more abstract) notion of
reproductive excess" is! Wanna play? Or should I take my ball and
go home?
.
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