Path: utzoo!utgpu!watmath!uunet!bionet!uw-evolution.uucp!joe
From: joe@uw-evolution.UUCP (Joe Felsenstein)
Newsgroups: bionet.molbio.evolution
Subject: Mutation and catastrophes
Message-ID: <8811220835.AA05051@uw-evolution.UUCP>
Date: 22 Nov 88 08:35:34 GMT
Sender: daemon@NET.BIO.NET
Lines: 25


Dan Davison's comment on how molecular evolution relates to catastrophic
selection events seems basically correct but perhaps agonizes too much
over something that doesn't need much agony.

Molecular mutations are the source of all genetic variability, so
no matter how many Death Stars hurl comets at the earth, when species
change that is still "molecular evolution".  It is just that in those
cases the rates and kinds of molecular change are affected by these
events.

Neutral mutation, surely the majority of changes in the DNA, goes on at
the same average rate per generation whether there are comets or no.
There are all sorts of subtleties (such as what determines the generation
time and how population size affects the standing level of neutral
variation in a population) but basically the neutral and selected
changes can be regarded as going on independently of one another and
as both being "molecular evolution".

Joe Felsenstein
 Dept. of Genetics SK-50, Univ. of Washington, Seattle WA 98195
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