john_SPAM{at}wilkins.id.au (John Wilkins) wrote in
news:c7hmdm$i0l$1{at}darwin.ediacara.org: 

> 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.


It is interesting that both Tim and Jim chose this paragraph with which 
to disagree. While I appreciate the reference to the Darwinian conditions 
for selection, I am chiming in with my disagreement. First, species do 
"moremake", i.e. there are more species produced than survive. We know 
this because the overall number of species has increased over time (if 
you press me I will dig out the reference), yet we know that species go 
extinct. Second, at any level you care to name,  their properties _are_ 
inherited, at least in the case of allopatric speciation, which is AFAIK 
generally agreed to be the dominant mode of speciation. The two species 
start off as identical except for geographic location, and it is only 
drift and in some cases differential selection to a slightly changed 
environment that causes speciation. In my book identical means sharing 
all properties. 

So we are left (assuming you agree with my first two points, and I 
suspect you may have a problem with the second) with whether differential 
survival of the excess species is due to the inherited properties. Now 
here is where I agree with half of your argument. The differential 
survival can be explained by the competition between individuals of the 
different species, based only on individual characteristics. Where I 
disagree is whether this is the parsimonious explanation. In some cases 
it may be necessary to compare individual differences to determine why 
one species survived in a competition while another did not. But in many 
cases it is simpler to compare differences at a higher level. Komodo 
dragons do not survive competitions with tigers. For the most part, 
marsupials do not survive competitions with eutherians. In this case the 
lower level explanation is valid but a waste of time.

Yours,

Bill Morse
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