"John Wilkins"  wrote in message
news:c7ph34$1gh$1{at}darwin.ediacara.org...
> Perplexed in Peoria  wrote:
>
> > "John Wilkins"  wrote in message
> > news:c7mqjd$262r$1{at}darwin.ediacara.org...
> > > Perplexed in Peoria  wrote:
> > >
> > > > "John Wilkins"
 wrote in message
> > > > news:c7hmdm$i0l$1{at}darwin.ediacara.org...
> > > > [snip much]
> > > > > As Eldredge noted, species do not
"moremake" in the requisite
manner
> > > > > to be subject to selection. They split, bud and
become disrupted,
> > > > > but at the species level their properties are not
inherited. The
> > > > > principle of parsimony suggests that if we can
account for what
> > > > > happens in terms of a lower-level process (i.e., a
population
> > > > > genetic process) then the higher level explanation
is otiose.
[snip
> > > > > remainder]
> > > >
> > > > I believe that your arguments don't apply to the kind of
> > > > species-selection that I describe in my latest response to Guy.
> > > > Population structure can be heritable if that structure
is an ESS.
> > > > Fluctuations from that stable structure are repaired.
> > >
> > > Subtle. But is an ESS a species-level property or a population-level
> > > property? By this I mean, is it a property that must be borne by the
> > > entire species rather than by parts of it - is it an ESS in a
population
> > > because the boundary conditions of that population form that trade-off
> > > to be stable, or is it something that must apply to entire species?
> >
> > The ESS doesn't *have to* apply to the whole species, but by the
> > definition of a biological species, it usually will.
>
> I'm not sure about this. An ESS is, by definition, local to a deme and
> its exigencies. If a population exists in a slightly (or greatly)
> different selective regime (= environment), it may maintain a different
> ESS using the same alleles - all that is happening then (WRT the alleles
> in question) is that there is a flow of genes between populations, each
> of which will settle into an ESS (or not, depending on the dynamics, but
> assume they do).
>
> Hence, it does not follow that we must treat a multidemic biospecies as
> a single deme with a species-wide ESS.

Hmmm.  I think that I am just now beginning to understand your
argument.  Let me know if I paraphrase it correctly.  "Even though
a trait may be a species-level trait, in that there is no variation
for that trait within the species, Jim's proposed mechanism of
species-level selection for that trait would also work as a mechanism
of population-level (or group-level) selection if the species did
vary for that trait.  Group-level selection is still group-level
selection, even if the group in question is the entire species.
Therefore, we don't need the concept of species-level selection."

If that is what you are saying (approximately), then all I can do
is to point out (again) that the species level is special in that
there are no disruptive gene flows to disrupt the frequency-
dependent equilibrium which I take to be crucial to a polymorphism
being heritable.  But, since you have heard that before, I
suppose we will just have to agree to disagree.  Unless, that is,
I have completely misinterpreted your position.

The only other possibility seems to be that you are disputing, as a
matter of fact, that there exist any species-level frequency
dependent equilibria that are stable in the sense that any
sub-population that switched to a different equilibrium would either
be forced back to the global equilibrium by gene flow or would be
induced to erect reproductive barriers.  And I can't believe that you
would adopt that position of fact.
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