Re: Fundamental Darwinism

On Thu, 9 Feb 2006 15:38:10 -0500 (EST),
Perplexed in Peoria <jimmenegay@xxxxxxxxxxxxx> wrote:
"Larry Moran" <lamoran@xxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:dsek61$16jt$1@xxxxxxxxxxxxxxxxxxxxxx
On Tue, 7 Feb 2006 23:57:00 -0500 (EST),
Perplexed in Peoria <jimmenegay@xxxxxxxxxxxxx> wrote:

[snip]

Steven Rose wrote,
However, whilst this is a mechanism of evolution, it is, as Darwin
himself recognised, not the only one. It is good at explaining how
species get better at doing their species thing, but [NS is] bad at
explaining how new species emerge. For this one needs other factors,
like founder effects, and above all sheer contingency - chance.

I think that the core of the Darwinian/NS explanation of speciation
is basically right. Speciation happens because a species occupies
two different environments, and it cannot adapt to both of them without
fissioning.

You are defending Fundamentalist Darwinism. I think you're wrong.
I believe that modern evolutionary theory does a much better job of
explaining speciation than the old-fashioned Darwinian theory that it
has replaced. Speciation mostly occurs by accident and adaptation is
not involved.

True enough if most speciation is allopatric.

Do you think that some other form of speciation is more common?

But even here, adaptation can be involved.

I'm not arguing whether adaptation *can* be involved. I'm arguing with
your initial statement (see above) where you imply that adaptation
*must* be involved and natural selection (Darwinism) explains it.
I think you're wrong about that. Dont be so quick to rule out random
genetic drift and accident.

As soon as you admit to those other possibilities then you're no longer
talking about "Darwinism/NS." Instead, you're moving into the 21st century
where we've gone beyond Fundamentalist Darwinism.

The key moment in an allopatric speciation is when the ranges of the
two species remerge.

Yes, that's when the test happens. The evolution happened earlier.

The argument can be made on ecological grounds that if there is not a
difference between the two species in what kinds of habitats they are
adapted to, then it is likely that one of the two is going to go rapidly
extinct.

That's the adaptationist point of view. You begin from the point you're
trying to prove. The real question is "what caused the differences between
the two populations so that they are now different species?"

You attempt to answer that question by *assuming* that they have diverged
by adapting to different environments then implicitly assuming that this
adatation will have led to genetic isolation by natural selection. Don't
you see the problem? The very way you phrase the question rules out
random genetic drift and accident. Your mind is already made up before
you even discuss the possible solutions.

And if there is a difference in adaptation, then selection is involved -
species-level selection, which is still 'fundamentalist' though not
'neo-fundamentalist'.

Imagine the two separated populations as they are evolving. They don't
see each other genetically. They evolve independently along pathways that
alter the way they mate and/or reproduce. Enough changes take place
so that when they come back into contact they can't interbreed.

How can there be *selection* against interbreeding? Isn't the reproductive
isolation just an accidental consequence of independent evolution over a
long period of time? Can't it be due to *any* of the mechanisms of evolution
and not just natural selection?



Larry Moran





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