From: Jkr438@aol.com
Date: Mon 05 May 2003 - 03:38:17 GMT
In a message dated 5/3/2003 8:36:33 AM Central Daylight Time,
rrecchia@mail.clarityconnect.com writes:
I'm reading "Darwin's Cathedral" by David Sloan Wilson and I have a general
evolution question. Suppose a species initially evolves under
circumstances where there is an advantage to having a drab grey color to
provide circumstances. Then suppose circumstances change so that spot
provide more of an advantage. Over time the species evolves an elaborate
biochemical mechanism for spots that allows the species to survive
effectively in this new environment. Next suppose the environment changes
back so that drab grey is now more effective. Organisms can go back to
drab without unevolving the entire mechanism for spots. Instead they can
just have point mutations that disable the spots. Then if the environment
changes again so that spots are better, instead of re-evolving the whole
spot system again, all that is necessary is that a few individuals lose the
point mutations preventing spots from being expressed. This means that
spots can reappear much more quickly the second time than they did the
first time.
So my question is, are there any real examples of this occurring in
nature? Is there a term that is used to describe this phenomenon?
[Jake] I haven't actually read this book, and I haven't been too active on
this list in a while but this one caught my eye. I don't really know if
there is a term for this whole process that you describe, but I do know that
the word "atavism" covers at least some of what you describe, and here is one
dictionary entry that I think comes closest: 1 a : recurrence in an organism
of a trait or character typical of an ancestral form and usually due to
genetic recombination
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