On Sep 24, 2005, at 4:15 PM, [EMAIL PROTECTED] wrote:
It does not happen with a single random mutation but in fish living in
caves
with no "need" for eyes genetic drift will ocur and without the
selection
pressure that favors those with vision there will be a loss of vision.
There may
also have been some advantage to the sightless (or poorly sighted
individuals)
that gave some advantages over the sighted fish.
Yeah; the information for making eyes has not been lost. It's still
there. But the gene codes that grow eyes have been switched off.
I'd imagine the advantage is that eyes take energy to grow, energy
which could otherwise be used for feeding and breeding. Thus the
sightless versions, using less energy to grow eyes, had a slight
breeding advantage over their sighted cousins. That slight advantage
would probably have needed no more than a few dozen generations to
fully manifest.
So while it could have taken hundreds or thousands of years for the
sightless variety to surface, it probably only took a couple of decades
for them to become the dominant form.
Additionally, we're talking about an isolate group, which tends to
focus mutations rather than allow them to spread out among a more
general, wider-ranged population. Think inbreeding here.
--
Warren Ockrassa, Publisher/Editor, nightwares Books
<http://books.nightwares.com/>
Current work in progress "The Seven-Year Mirror"
<http://books.nightwares.com/ockrassa/Flat_Out.pdf>
<http://books.nightwares.com/ockrassa/Storms_on_a_Flat_Placid_Sea.pdf>
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