Tim Tyler  wrote in news:brb1nu$2o6p$1
{at}darwin.ediacara.org:

> I've written a brief essay about Eörs Szathmáry's
> influential "Stochastic corrector" model - and my
> view of its relevance to the origin of life.

(snip)
 
> Overcoming differential reproductive rates
> ------------------------------------------
> What about the possibilty that one sort of replicator will 
> wipe out the other ones? Rather than invoking selection 
> between ecosystems to explain this, I suggest considering 
> the possibilities of: 

 
> * Frequency-dependent selection
> 
>   Frequency-dependent selection is the reason why foxes don't
>   wipe out rabbits - (when the rabit population goes low, the
>   fox food supply decreases) and similarly why rabits don't
>   out-reproduce foxes (when there are lots of rabits around,
>   the fox has an easy time of feeding and reproducing). These
>   sorts of forces will act within most ecosystems anyway -
>   there is no need to invoke selection between ecosystems to
>   explain how a diverse range of species is maintained within
>   them.

Assuming that your group of replicators is not competing for exactly the 
same precursors, and assuming that a number of the replicators produce 
byproducts that are the precursors for other replicators, then chemical 
equilibria will serve the same function of feedback to regulate the 
overall rates of replication by chemicals in a "pool" that frequency- 
dependent selection does for organisms in an ecosystem.Thus it seems 
quite possible that "pools" of chemicals could maintain significant 
diversity.  Such systems would however be more susceptible to extreme 
oscillations than modern ecosystems.


Yours,

Bill Morse
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