Re: Plausible evolutionary scenario for metamorphosis?

On Nov 16, 8:53 pm, r norman <r_s_norman@xxxxxxxxxxxx> wrote:
On Fri, 16 Nov 2007 16:18:45 -0800, Mark Isaak <eci...@xxxxxxxxxxxxx>
wrote:

On Fri, 16 Nov 2007 10:00:23 -0500, r norman wrote:

On Nov 15, 1:22 pm, pineapple.l...@xxxxxxxxx wrote:
Plausible evolutionary scenario for metamorphosis?
[...]
Metamorphosis is an ancient and very widespread phenomenon . . .

In fact, Ovid wrote a whole book on the subject.

Here, however, is a reference which may be more what you are looking for:

Truman, J. W. and L. M. Riddiford, 1999. The origins of insect
metamorphosis. _Nature_ 401: 447-452.

That's the problem with t.o. --- just whenb the discussion gets good
and heated, somebody goes and injects fact into it. Spoils all the
fun!

A nice review of their work is at
http://www.artsci.washington.edu/news/Winter00/metamorphosis.htm

The problem I have with this is that insect metamorphoses is just one
example. There are rather large changes in life form in a very large
number of different animal phyla. The parasitic flatworms are
notorious for having multiple forms with very different ecologies
(hosts). That hormones are responsible for the metamorphic event
doesn't really explain its evolution.

Just so I am clear here, it is your belief/conviction (whatever) that
the larval stage in insects arose from variation in the juvenile stage
rather than modifications/extensions of the egg stage?

Note that I don't have a problem with this since lose of
function/features from the juvenile stage probably requires
fewer and simpler steps than adding to the egg stage.

Initially I just wanted to insure that pineapple had a simple
reply that he could understand. I wonder if he even read any
of the replies, or has this all been for nothing.

Thanks;

Friar Broccoli
Robert Keith Elias, Quebec, Canada Email: EliasRK (of) gmail * com
Best programmer's & all purpose text editor: http://www.semware.com

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