From: colby@bu-bio.bu.edu (Chris Colby)
Newsgroups: talk.origins
Subject: some stuff about fruit flies
Date: 7 Oct 92 02:00:59 GMT
Organization: animal -- coelomate -- deuterostome

In article <7196@tekig7.PEN.TEK.COM> alanf@tekig6.PEN.TEK.COM (Alan M Feuerbacher) writes:

[Alan is quoting someone else here]
>  If left alone
>  for a few generations, even the most severely mutated flies that
>  retained their fertility returned to normal or something close to it.

This is simply false. Numerous mutant strains of Drosphila are
propagated for genetic studies, the reversion rate is a function
of what sort of mutation is involved. A single point mutation has a
small chance of reverting to "wild-type"; deletion mutations don't
revert (as part of their gene is missing) unless a suppressor
mutation can compensate. I know a guy (a friend of my advisors)
who keeps stocks of flies with legs growing out their heads and
they keep chugging along pumping out leg-headed flies. 

My research organism is the fruit fly (_Drosophila melanogaster_).
Culturing mutant strains is no problem, if it was there would be
no modern genetics as the fruit fly is _the_ model for eukaryotic
genetics. On this point the author is clearly ignoring reality.

(As a sidenote, there is a place that stockpiles Drosophila mutants
and sends them to researchers on request. They publish a book that
lists all their different stocks -- it's a _big_ hardbound volume.
If all mutant strains reverted within a couple generations, they
would only have to print a pamphlet 8-)

>  But when Morgan carried the
>  experiment further, inbreeding this new eyeless strain, he found that
>  within a short time, perfectly formed eyes appeared! 

Does the book give an actual ref, what experiment exactly did
Hunt perform? From the paucity of information given, this
could simply be showing a dominant knockout mutation (i.e.,
"eyeless" masks the "eye" allele in heterozygotes). In order
to interpret this, the author should have given what crosses
were performed and what percentage of the offspring reverted
to the "eyed" form. If he has such a good case against evolution,
why is he being so vague?

>    The traditional explanation of this remarkable phenomenon is that
>    the other members of the gene-complex have been `reshuffled and
>    re-combined in such a way that they deputise for the missing normal
>    eye-forming gene.' 

Straw man alert. As another poster insightfully posted, the absense
of a phenotype does not imply the gene itself is damaged or missing;
the control region (the on/off switch if you will) could be broken.
You can induce teeth growth in birds if you treat them with the
right hormones, the functional genes are still there, but the genes
regulating them have changed.

All these arguments fall just short of containing enough information
to tell precisely what is going. The problem for creationists
when trying to construct arguments that sound more like science is
people will treat them like scientific arguments. 

>Alan Feuerbacher

Chris Colby 	---	 email: colby@bu-bio.bu.edu	---
"'My boy,' he said, 'you are descended from a long line of determined,
resourceful, microscopic tadpoles--champions every one.'"
 	--Kurt Vonnegut from "Galapagos"

Newsgroups: talk.origins