Guy Hoelzer  wrote in
news:blss5r$2dsa$1{at}darwin.ediacara.org: 

> in article blo8d7$18eq$1{at}darwin.ediacara.org, William Morse at
> wdmorse{at}twcny.rr.com wrote on 10/4/03 9:58 PM:
 
>> Guy Hoelzer  wrote in
>> news:blciii$177j$1{at}darwin.ediacara.org:

>>> Because it is still rather inconceivable to me how natural selection
>>> can operate when the reproducing agents exist at a scale of
>>> organization different from that where fitness is manifested (others
>>> might prefer to word "evaluated" here), I hope that
you (or anyone)
>>> can explain it to me.  I am not aware of any logical explanation
>>> being provided by Dawkins, and IMHO there is no such logic.
 
>> I fail to understand this last paragraph. Clearly reproducing agents,
>> whatever their scale, are not the same as fitness agents. As you note
>> above genotypes are influenced by environmental effects, but not all
>> of these are heritable. Since the disconnect exists in any case, why
>> does the scale matter? Evolution is constrained by the realities of
>> DNA structure and function, even if that reality is not accurately
>> depicted by the concept of "gene". So natural selection
does operate
>> with reproducing agents being different from selected agents,
>> conceivability notwithstanding.
 
> I don't buy your argument. 

You mean I don't even get two cents for my two cents worth? :-)

> I never said that reproducing agents are
> only manifested at one level and my position is not compromised by
> that reality. My argument is that the process of selection can
> manifest independently at any level of organization where there are
> reproducing agents exhibiting heritable differences in fitness.  Can
> you explain further how you think natural selection can operate when
> there are no heritable fitness differences among reproducing agents?

I have no problem with selection at different levels of organization, and 
I can agree that reproduction occurs at different levels, but I think 
that as a general rule reproducing agents _do not_ exist at the level 
where selection operates. I would argue that instead they exist _one 
level down_ from the level where selection operates. Let me illustrate:

My body is not a reproducing agent as far as my body is concerned- it is 
composed of cells that are. But my cells (for the most part) do not have 
heritable fitness differences as individual cells, only as my body.

A pack of wolves is not a reproducing agent as far as the pack is 
concerned - it is composed of individual wolves that choose to join or 
stay in the pack. But invidual wolves without a pack will not survive 
long, so their heritable fitness differences depend on the fitness of the 
pack. 

Now let us consider lichens. Lichens are not a reproducing agent, they 
are composed of members of two different species that must reproduce 
separately. But without the other species, the individual species will 
die, and hence in isolation can have no heritable fitness difference.

The reason why selection can still operate when the scale of reproducing 
agents is different from that at which fitness is manifested(note that 
the reproducing agents still have heritable fitness differences) is that 
every higher level of organization is composed of groups of agents at 
lower levels. So anytime a fitness event affects the higher level  it 
will automatically affect the lower levels comprising it. When I kill a 
pack  of wolves, I kill the individual wolves, and I kill their cells, 
including the DNA in the cells. (I don't know if it is of interest that I 
do not kill all the chemicals in the cells, nor do I destroy all of the 
microbiota that inhabit the wolves).

Yours,

Bill Morse
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