Text 73, 138 rader
Skriven 2004-09-16 13:02:00 av John Edser (1:278/230)
Ärende: The Darwinian Maximand
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> >>>RN:-
> >>>snip<
> >>>In a small population, it is quite possible (even very likely) that
> >>>the abundance of a particular allele might change just be chance over
> >>>generations.  For example, those individuals with big noses just
> >>>happened to have more babies with big noses than expected.  It is sort
> >>>of like flipping a coin twice. You expect one head, one tail, but
> >>>sometimes you end up with two heads. That is the definition of genetic
> >>>drift: a change in the genetic composition of the population (in the
> >>>allele frequencies). 

> > JE:-
> > Of course, RN has _not_ eliminated Darwinian natural
> > selection from the proposed drift process so that RN's
> > conclusion that genetic drift is alone causative remains 
> > incorrect. Clearly, if "those individuals with big noses just
> > happened to have more babies with big noses than expected"
> > and raised more big nosed offspring to fertile adulthood
> > then any assumption that "just happened" was ONLY chance
> > remains utterly incorrect.
> > 
> > I have described an experiment that can eliminate all
> > natural selection within an _expanding_ population 
> > only allowing genetic drift as causative to allele
> > freq. changes. All you have to do is artificially
> > force all members of one population to raise the
> > exactly the same number of fertile forms to adulthood
> > where this number is larger than just a parental
> > replacement value.  The prediction is: all natural 
> > selection must be halted within this experiment while 
> > Darwinian fitness equality can remain enforced. Thus only 
> > genetic drift (which cannot be eliminated) is now left 
> > to cause "evolution". 

> BOH:-
> No, you've deleted drift as well.  The only way drift can be 
> re-introduced is for there to be genetic variation within a family 
> (through segregation), but in this case you can no longer guanrantee 
> "Darwinian fitness equality".  In other words, this doesn't allow you to 
> have your cake and eat it.
> If you want to eliminate drift, then you need an infinite [effective] 
> population size.

JE:-
Dr O'Hara's reply seems to be completely 
confused. At the start Dr O'Hara 
comments: "you've deleted drift as well" 
when such an event is just experimentally 
impossible.  This is because (via BOH's own 
conclusion) "if you want to eliminate drift, 
then you need an infinite [effective] 
population size" which is an impossibility.

I never suggested an intention
to delete genetic drift simply because 
I could not do so even if I wanted 
to. My only intention was to delete Darwinian
natural selection for a significant time period.
This would allow a test of drift acting alone as
causative to "evolution" as well as my 
definition of Darwinian fitness: the total 
number of fertile forms raised to 
fertile adulthood by each parent within 
one population. Dr O'Hara appears to have 
entirely missed my point. The experiment 
is only designed to delete Darwinian natural 
selection while leaving genetic drift for 
sufficient time to test to refutation:

1) "Drift as evolution".
2) My definition of Darwinian
fitness as causative to evolution.

My predictions for this experiment 
are:

a) Drift acting alone without selection 
for a significant period of time
within an expanding population will
only cause the dissolution of all
the individuals within that population.
Unless "dissolution" is redefined as
"evolution", drift without selection
cannot validly claim to cause "evolution".

b) Darwinian fitness (as I have defined
it) would be tested to refutation as the
only objective fitness that exists within
evolutionary theory. No other proposition
of fitness exists that can halt all selection
within a natural population.

c) Only a single level of selection
would now be required within evolutionary 
theory.

The above would pave the way to:

i) Allow the rule: absolute fitness
cannot be selected to be lowered.

This would refute Hamilton's premise 
that organism fitness altruism (OFA) 
can evolve within nature as measured
by Hamilton's (uncorrected) rule.

ii) Argue that only absolute fitness 
mutualization producing organism fitness 
mutualism (OFM) can exist within nature 
for all Darwinian fitness association ESS's 
(evolutionary stable strategies).

iii) Argue that Darwinian fitness (as I 
have defined it) is the biological maximand.


Regards,

John Edser
Independent Researcher

PO Box 266
Church Pt
NSW 2105
Australia

edser@tpg.com.au
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