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RE: CNN article on radical mutation/doomsday genes

On Sunday, November 29, 1998 8:58 PM, John V Jackson 
[SMTP:jjackson@interalpha.co.uk] wrote:
> --Original Message-- From: Betty Cunningham <bettyc@flyinggoat.com>
> 29 November 1998 23:24
> I was concerned by this paragraph in it:

> "Evolution is often thought of as incremental," said biologist Andrew
> Cossins of the University of Liverpool in England. "But the fossil record
> contains many examples of apparently rapid changes in body form. This
> mechanism provides, for the first time, a means by which changes in body
> form can be substantial and stepwise rather than progressive."


> In fact, if it were true, it would only cause punctuated evolution in
> response to abnormal heat.

There is at least one trivial explanation for these results.  Can the results 
be distinguished from any environmental stress that causes a partial breakdown 
in the regulation of meiotic crossing over?  In other words, are we looking at 
a roughly random assortment of frameshift and unequal cross-over errors?  From 
a genetic point of view, how can a mechanism that significantly reduces the 
overall fitness of progeny be selectively favored?  Sure, there's a chance that 
you might produce a line that has some advantage under the new conditions. 
 But, much more often than not, this mechanism would simply hasten the demise 
of an already marginal (for the new environment) species.

  --Toby White