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From: ethan@utastro.UUCP (Ethan Vishniac)
Newsgroups: net.origins
Subject: Re: Innocent Question
Message-ID: <85@utastro.UUCP>
Date: Mon, 13-May-85 13:40:11 EDT
Article-I.D.: utastro.85
Posted: Mon May 13 13:40:11 1985
Date-Received: Thu, 16-May-85 04:00:40 EDT
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Distribution: net
Organization: U. Texas, Astronomy, Austin, TX
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> I was just wonderin'... If evolution happened in abrupt
> changes, wouldn't two animals have to undergo the same
> (or a similar) change? I mean, if in each step the new
> species can't breed with the old, we would need two of
> the new species in order to get something started. 
> What's the chance that there are two animals, 1 male and
> female, within the general vicinity (close enough so that
> they could find eachother), undergo the same drastic change
> in the same generation?

This is an irrelevant question.  Punctuated equilibrium "jumps"
involve a few thousand (or even hundred years) not a single generation.
A  mutation that drastically changed an animal in a single generation
would involve a single gene.  Either the new animal would still be able
to breed with the rest of the population (most of the barrier to crossbreeding
is biochemical and would be unlikely to be correlated with a particular
structural change) or it wouldn't.  If it wouldn't then the mutation would
as you say, have to be a common one to provide the basis for a new species.

"Don't argue with a fool.      Ethan Vishniac
 Borrow his money."            {charm,ut-sally,ut-ngp,noao}!utastro!ethan
                               Department of Astronomy
                               University of Texas