Several questions on evolution, and mutation (rate)
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
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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