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Re: K-T Theories

>From: uunet.uu.net!murphy!acmcr!vr@lepomis.psych.upenn.edu (Vicki Rosenzwe > 
 > The problem with this is that it assumes that viruses are
 > ideally designed--a newly virulent virus mutation might wipe
 > out its host population, then die out itself because it had no
 > more hosts. 

Actually it doesn't really.  All that it assumes is that contagion
requires aproximate contact, so that small isolated pockets of
the host species will not cross-infect, and that the initial
pandemic does not completely wipe out the host species directly.

This very pattern is seen with rabbits in Australia, where the
disease that was introduced to control them remains more or less
rare except when there is a population boom of rabbits, and then
a new epidemic rages through the newly merged populations reducing
the numbers back to small levels.

 >Or, equally plausible, a virulent virus might wipe
 > out all but a small remnant population, which then succumbed
 > to the sort of chances that a large population can survive--a
 > flood, say, or a couple of years in which no eggs hatch.

Of course you are right that such small isolated populations are
far more susceptible to random bad luck.

swf@elsegundoca.attgis.com              sarima@netcom.com

The peace of God be with you.