Several questions on evolution, and mutation (rate)

James Foster foster at cs.uidaho.edu
Fri Sep 6 10:36:10 EST 1996


Ram Samudrala (ram at mbisgi.umd.edu) wrote:

: >For example, genes which code for one protein in hemoglobin may
: >silently duplicate, and only over much time will that duplication
: >develop some functionality.

: This is what I mean by evolution!  Suppose our haemoglobin genes
: tomorrow also conferred resistance to malaria (by having a few
: mutations).  Wouldn't you wonder HOW a new function arose from this
: duplication (which must've been both haemoglobin initially), and how
: long it took just to come up with it?

: >It's pointless to insist on isolating the original duplication event,
: >because it was silent.

: No, not the original duplication event, but the length of time (and
: how) it takes to come up with the new functionality (which has to
: happen BEFORE natural selection).

Ahhh...gotcha.  That is indeed an interesting question.  I'm not sure
what the answer is.  I know that many new functions are co-opted from
similar functions (I think the classical example is some enzyme
beginning with the letter l...but can't remember right now).  But that
begs the question of where the co-opted behaviors came from.

Similarly, hybridization is a good source of new behavior.  But again,
you have to have the hybrids to begin with.

Still, evolution is a change in distribution of characters...you are
focusing on one particular change: from zero to non-zero distribution.
That is interesting, and important.

: >The important point is that mutation without selection is not a
: >particularly interesting concept, from an evolutionary perspective.

: We disagree there too, and there's quite a bit of research on this
: topic.  Basically, the idea is, how long does it take for new function
: to evolve, from an existing gene, before naturally selection can
: operate on it.  How does it evolve?  Is it randomly (the current
: belief) or is there some directed process going on?

OK.  You convinced me.  Mutation in isolation is an interesting thing to
study.

I have seen the new evidence supporting some Lamarkian mechanism, so
your last question does merit some investigation.

Thanks for the discourse.  I'm outta here.
--
James A. Foster			email: foster at cs.uidaho.edu
Laboratory for Applied Logic	Dept. of Computer Science
University of Idaho		www: http://www.cs.uidaho.edu/~foster

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