Several questions on evolution, and mutation (rate)

Oladele A. OGUNSEITAN oaogunse at UCI.EDU
Fri Aug 30 14:54:43 EST 1996



On 30 Aug 1996, Larry Edwards wrote:

> David Beorn (dbeorn at freenet.vcu.edu) wrote:
> : On 27 Aug 1996, Joan Shields wrote:
> 
> : > From: Joan Shields <joan at med.unc.edu>
> : > Just look at how variable HIV is.  All these mutations all occuring at the
> : > same time - some are viable and some aren't.  Some are better at surviving
> : > for a while or better at transmission or better at eluding drugs and the
> : > body's own systems.  
> 
> : But in all cases, it is STILL HIV, right??  I.e. no evolution occurred - 
> : adaptation, variability of a species yes - but not evolution.  No new 
> : "creature" was created.  
> 
> In Webster's the biological definition of a species is given as:
> 
> "...related organisms or populations potentially capable of interbreeding."
> 
> The creation of new species is "speciation" ... evolution can exist
> without speciation. The definition of evolution (according to Webster) is:
> 
> 5a: the historical development of a biological group (as a race or
>      species): PHYLOGENY
> 5b: a theory that the various types of animals and plants have their
>      origin in other preexisting types and that the distinguishable differences
>      are due to modifications in successive generations
> 
> Darwin's hypothesis (I think) was that evolution caused speciation.
> 
> I think it is fair to say that there is direct evidence of evolution,
> but only circumstantial evidence that evolution resulted in speciation
> (there may be direct evidence of this too, but I don't know of it).
> 
> Larry EDwards
> 
> 
> 


	There is the lurking suspicion that Darwinian definition of 
evolution and speciation are based on tautological hypotheses  (see 
PETERS, R.H. 1991. A CRITIQUE FOR ECOLOGY. Cambridge University Press). 
If the ultimate criterium for a species is interbreeding, then, this 
concept is becoming more and more meaningless in the age of genetic 
engineering. What do you call a laboratory mouse carrying a luciferase 
genes of a firefly ?. Afterall, breeding does mean the ability to "mingle 
the genes". Indeed, in bacteriology, the concept of 
species has been very difficult to pin down.  But we have a convenient 
(systematic) phylogenetic arrangement to satisfy our academic curiosities.   

MUTATIONS occur in parallel, and the likelihood of a successful 
mutant is dependent on the population size and the size of the genome. 
It seems to me however that evolution is a linear event because here, 
ENVIRONMENTAL selection is a critical factor.  That is why it has been 
possible for natural history to trace the lineage of organisms and to 
construct phylogenetic trees.

This has been the argument of the "DIALECTICAL BIOLOGISTS" - that the 
strict Darwinians often neglect "environmental evolution" which would 
take place in spite of biological organisms - indeed, in their absence.  
What's missing is rigorous modeling of the coevolution of life and 
environment as it constrains the scalar and vectoral parameters of 
successful mutants.


- Dele Ogunseitan

University of California
Irvine 92697-7070



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