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Path: utzoo!watmath!clyde!cuae2!ihnp4!aicchi!dbb
From: dbb@aicchi.UUCP
Newsgroups: sci.bio
Subject: Re: The Red Queen
Message-ID: <888@aicchi.UUCP>
Date: Sat, 10-Jan-87 13:49:03 EST
Article-I.D.: aicchi.888
Posted: Sat Jan 10 13:49:03 1987
Date-Received: Sun, 11-Jan-87 06:52:01 EST
References: <741@aecom.UUCP> <927@husc6.UUCP> <124@bcsaic.UUCP>
Reply-To: dbb@aicchi.UUCP (Burch)
Distribution: na
Organization: Analysts International Corp; Chicago Branch
Lines: 34
Keywords: Blind fish, Caves, Philogeny
Summary: Thoughts on cave life. Pure speculation.

In article <124@bcsaic.UUCP> michaelm@bcsaic.UUCP (Michael Maxwell) writes:
>
>I suggested this in answer to an exam question once, as the origin of blind
>(eyeless) cave fish.  (The incidence of eyeless fish is quite high, but for
>obvious reasons the eyeless ones seldom make it very far in life up here.)
>The professor didn't like my answer...his point was that there had to be a
>selective advantage to blindness in cave life.  I didn't believe so at the
>time, and I'm still skeptical.  Anyone care to comment?
>-- 

Well... Some thoghts on this;  First, it seems to me to be possible that traits arise that are simply no DISadvantage.  These traits may have disadvantageous 
effects in a different environment, but are OK in the special environment in
which they arise.  Blind fish would not survive well in a sunny pond.

After some number of the population is blind, we must THEN start to look for
some advantage to blindness.  Perhaps the production of dyes for use by the
retina saps the cave fish of amino acids that are not often found in his
world.  If there were a small famine due to unusual surface conditions, the
sighted fish might die faster than the blind ones.  Repeat this pressure many
times over thousands of years, and you have a totally blind fish population.

It is also possible that the sighted fish have a smaller range than the blind
ones.  They might choose to remain in the parts of the cave where light filters
in from the surface.  The blind fish, with no such tropism, would be free to
populate the nether regions...

Any constructive thoughts on these opinions?

-- 
-David B. (Ben) Burch
 Analysts International Corp.
 Chicago Branch (ihnp4!aicchi!dbb)

"Argue for your limitations, and they are yours"