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From: trin0008@sable.ox.ac.uk (Rick Heylen)
Subject: Re: Lamarckian Evolution
Message-ID: <1995Feb24.020541.4049@inca.comlab.ox.ac.uk>
Organization: Oxford University, England
References: <1995Feb4.005816.16390@gdunix.gd.chalmers.se> <3i5nvj$7ki@mailer.fsu.edu>
Date: Fri, 24 Feb 95 02:05:41 GMT
Lines: 34

Imagine an environment where the temperature oscillates every few days between
two extremes- hot and cold. There are bacteria living in this environment and
metabolising food and reproducing. The type of bacterium which reproduces
well in the hot environment doesn't do so in the cold environment and 
vice versa however there is only a small genetic change necessary to 
interconvert them. Imagine that there was one bacterium which produced
children which were adapted for hot conditions when the temperature was rising
and cold conditions when the temperature dropped. Imagine that this bacterium
also passed this adaptive trait on to all it's children regardless of whether
they were hot-adapted or cold-adapted. Now this bacterium would be the fittest
type in the soup and there's no real reason why it can't occur. Eventually
it probably would occur.
If the change required to specialise the bacteria was at a very fundamental
level in the bacterial specification then we would have a sort of limited 
Lamarkianism. Of course evolving webbed feet or longer necks using Lamarkian
ideas is stupid as they're much more plausibly explained via normal Darwinian
evolution. In an environment where some factor critical to survival oscillates
in the space of about two or three generations then you could expect this sort
of thing to take place. 
It would be very difficult to prove however as you would have to show that
the change in the offspring was made at the genetic level, the change is
directly correlated with this environmental factor and that the increased 
fitness of the children is based mainly on the genetic change. Further
you would have to show that this DNA altering behaviour is also shown in the 
children and is reversible otherwise it's just an example of the parent
juggling the child's genomes  randomly  in the hope of making some change.

Lamark did come up with some really crackpot ideas and there's probably
a large knee-jerk factor in the dissmisal of MILD lamarkian type things
such as the above. If the above in infeasable or somehow subsumed by the
revised Darwinian theory of evolution then please inform me.

Rick Heylen
 
