Re: Natural Selection - Question

Brad Swanson (
23 Jan 1995 23:26:00 GMT

In article <>,
(Richard Spear) wrote:

> In article <> Brian Doyle
<> writes:
> >Subject: Natural Selection - Question
> >From: Brian Doyle <>
> >Date: 22 Jan 95 11:44:16 CST
> > If a species forces another species into extinction,
> > i.e. Humans hunting animals, either by pollution
> >or other conventional means, into extinction,
> > Is this considered Natural Selection??
> No
> Regards, Richard

Boy Richard, thanks for that indepth analysis of the situation. Any
reason why it wouldn't be considered natural selection? It certainly is
evolution, since evolution is the change in allele frequencies in a
population. What extinction
produces is a loss of all the alleles for that population. So evolution
is occurring, the forces of evolution are genetic drift, mutation,
assortative mating, migration, and natural selection. Hmm, which one of
these fits, not drift, as the extinction certainly wasn't a chance event,
wasn't a mutation, assortative mating couldn't do it, and the dispersal
patterns probably wouldn't do it either. Looks like we only have one
candidate left. That being said, it doesn't mean that we shouldn't worry
about driving species extinct. We are changing the world at a much more
rapid rate than new genetic material can be introduced to allow evolution
via natural selection to act. With mutation rates of around 1e-6 (at
least for nuclear non-repetative sequence DNA) we are asking the
populations to respond at a faster rate then they physically can. Is it
natural selection, I would argue not natural, the things we are doing are
not natural (pollution, global warming, etc) but maybe artificial.
However that is just in MHO. I suppose that it is not that different than
the mass extinctions produced at the K/T boundary and the other really big
extinctions. Rapid environmental change followed by mass die-offs as
organisms failed to find the genetic variation quickly enough to handle
the new situations. Anyways, a quick poll of the grad students here says
it is natural selection.

Brad Swanson ***The ratio of my incompetence ************
Dept. of Biology ****to the task at hand isinfinite!*******
Purdue Univ. *** Graduate school, the last legal***** ****form of indentured servitude******