Re: Haldane's Dilemma and quantitative genetics


"Wirt Atmar" <atmar@xxxxxxxxxxxxxxxxx> wrote in message news:e8nau1$25q$1@xxxxxxxxxxxxxxxxxxxxxx
ErikW writes:

I don't really doubt that more niches promotes adaptive evolution. But
as she writes: "natural selection acts to stop further change". So she
doesn't mean that all evolution stops, only adaptive. Selection affects
neutral variation only trough sweeps or background selection, otherwise
it can't do anything to stop them.

I could add several more examples to the cat case you quoted before
where authors have correlated environmental changes with
species-radiation age estimates. Despite the tentative nature of such
conclusions I agree with you that there's something to it.

I even have thought myself that perhaps competition induces phenotypic
evolutionary stasis but have had no real reasons for it other than
intuitive ones and I still don't (but I have never persued it). This is
an area where I am rather open to ideas.

Let me first apologize for being so long getting back to this.

As for the idea that intense competition induces phenotypic
evolutionary stasis, let me say that I'm relatively quite convinced
that it's true.

Hmmm. Let me be sure I understand you. You are referring to intense
*intraspecific* competition, right? Species whose members spend most
of their time and effort 'competing' against a hostile environment
are free (in your view?) to change their phenotype. Right?

I can see how that might be the case if the intraspecific competition
takes one of the forms of sexual selection. It is less clear to me
why this would happen if the competition is for resources.


.

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