Re: latent mutation

From: Sabrina Marr (
Date: Wed 07 May 2003 - 03:25:02 GMT

  • Next message: Scott Chase: "Re: latent mutation"

    oh, very nice lawrence. hm, if it will take around 300,000 generations to re-de-evolve, even at worst, and the environmental change that put the pressure on de-evolution is severe and sudden, the poor little organisms are going to go extinct. what an awful scenario! thank god there are no real life situations where this actually happens or we might not have termites. hm, even if it were to take only 2 generations to get a guaranteed beneficial point mutation in all of the genes that would be required to support the correct camouflage (yes, that's so likely to happen), the organism will die anyway because evolution only works in small intervals, not in an environment that changes drastically in very little time. isn't that why fish and insects go extinct? good luck with this hypothesis.

    always, sabrina

    ----- Original Message ----- From: "Lawrence DeBivort" <> To: <> Cc: "Ben de Bivort" <> Sent: Tuesday, May 06, 2003 1:42 PM Subject: RE: latent mutation

    > Greetings, Ray and all others,
    > I have been trying to follow this most interesting thread, with my
    > inadequate knowledge. So I turned to my favorite expert, my son Benjamin,
    > and this is what he wrote back:
    > (start)
    > Most mutations fall into
    > the following categories:
    > 1) Point mutation - a single base of DNA is modified due to environmental
    > stress such as mutagens, X-rays, or UV light. 3 types: These occur at
    > different rates by type, and those rates are determined by the
    > environmental conditions (mostly), and not the adaptive condition of the
    > organism. An organism can't do anything like "note it is not well adapted
    > and switch to point mutations only)
    > Deletion: a single base is removed. If this happens in a protein
    > coding region, it is likely to be very detrimental since it will screw up
    > the entire piece of the protein it is found in. I am working on a project
    > to detect evolutionary events where this has actually been beneficial.
    > Insertion: a single base at random is added in. Same effect on
    > coding regions.
    > Substitution: Either very harmful in coding regions (might
    > truncate a protein prematurely), somewhat harmful (by changing the type of
    > one amino acid in the protein in a bad way), or not harmful at all (a
    > silent 3rd base pair substitution in a codon, or causing an amino acid of
    > similar function to replace the old one).
    > A note: Any harmful mutation is also potentially beneficial, but harmful
    > mutations are much more frequent than beneficial. Insertions and deletions
    > are much less likely to be beneficial, since they change an entire chunk
    > of protein (rather than a single amino acid), and the likelihood that the
    > sum of all those changes is beneficial is low, relative to the likelihood
    > that a single amino acid change is beneficial.
    > 2) Inversions - a piece of a chromosome detaches and reattaches in the
    > opposite direction, can cause subtle changes in the expression of many
    > genes, and catastrophic changes in the expression of the one found at the
    > break point.
    > 3) Translocations - a piece of a chromosome detaches and reattaches in
    > the same orientation. See above. Down Syndrome is an example of this.
    > 4) Transposon insertion - certain pieces of DNA are self-replicating
    > within the genome. They can insert themselves at "random" into new places,
    > disrupting the expression pattern or coding sequence of a protein.
    > 5) Proviral insertion - viral DNA can insert itself into the genome. Same
    > effect as the transposon.
    > 6) Homologous recombination - has evolved in sexual organisms to swap
    > equivalent parts of one chromosome from the mother for equivalent parts of
    > the paternal chromosome. Doesn't add new mutation, but creates new
    > combinations of mutations that were originally found in the mother and
    > father. We think sex evolved as a mechanism to ensure recombination, but
    > no one really knows why recombination is good (which it almost certainly
    > is given how often it has evolved).
    > 7) Immunological recombination - in certain immune cells, the genome is
    > modified and parts are lost (in all other cells the genomes are
    > identical). This is to increase the diversity of molecules that the immune
    > system can recognize.
    > These are roughly ranked by the frequency of their contribution to
    > evolution.
    > As a general rule types 1,2,3,4,5 can happen anywhere in the 3,000,000,000
    > bases of the genome.
    > Once a trait has evolved away, it is often easier to "re-evolve" it than
    > to undo those mutations that caused it to go away. This would involve
    > undoing _specific_ mutations that already happened. For example, lets say
    > the likelihood is that per generation, 10 mutations will appear in the
    > next generation. And lets say to turn off a particular trait requires one
    > mutation to occur in one gene out of 10,000.
    > That means in 1 individual 10/10,000 = 1/1000 genes have been mutated. So
    > if we have a population of 1000 individuals, it is reasonable that in one
    > generation such a mutation will arise.
    > Now, if we want to _undo_ that particular mutation, it will require the
    > reverse mutation at that exact spot (not just in that exact gene). So at
    > 10 mutations per individual per generation, and 1000 individuals we have
    > ~10,000 new mutations per generation. But we are waiting for one mutation
    > in 3,000,000,000 now - and so it will take roughly 300,000 generations!
    > If undoing the mutation took two specific mutation reversals, it would
    > take approximately 90,000,000,000 generations.
    > I hope this helps.
    > (end)
    > > -----Original Message-----
    > > From: []On Behalf
    > > Of Ray Recchia
    > > Sent: Mon, May 05, 2003 9:15 PM
    > > To:
    > > Subject: Re: latent mutation
    > >
    > >
    > > Thanks for the effort Chris. Don't sweat it too much. I may try to
    > > Wilson after I finish his book and I'll see if he has any examples
    > >
    > > Jake, I think the term "atavism" is fairly close to what I'm looking
    > > but it doesn't seem quite the same. Atavism would seem to cover
    > > the stage
    > > where the spotting mechanism disappears with point mutations but not the
    > > potentially quicker re-evolution of the spots again when the
    > > environmental
    > > condition for their selection re-appears.
    > >
    > > The book 'Darwin's Cathedral' by the way has more to do with cultural
    > > selection of religions. The idea for latent adaptation came when he was
    > > discussing guppy species differences in response to different types of
    > > predation. Because the differences in predation seem to me to be things
    > > that might fluctuate within the environment on a fairly frequent basis I
    > > thought something like a 'latent adaptation' might end up present within
    > > the species.
    > >
    > > At 05:48 PM 5/5/2003 -0700, you wrote:
    > > >aren't point mutations those undesirable things that "bad" dna
    > > have? heh. I
    > > >don't think that species would evolve to include point mutations
    > > since this
    > > >would mean screwing up all of their dna. think more. if a species is
    > > >gray and spotted, when gray is good and spots are bad (since it
    > > >un-evolve the spots hm?) won't it like, get killed? that's not good.
    > > >selfish gene, by dawkins. best dna book out there.
    > > >
    > > >always, sabrina
    > >
    > > I don't think you got it. I'll spell it out a bit more clearly
    > >
    > > Under environmental condition 1 a bland grey animal is better
    > >
    > > Environmental condition 2 arrives. Grey bland animals are no longer the
    > > best camouflage
    > >
    > > Over time our species slowly evolves the ability to appear with
    > > spots. Under environmental condition 2 spotted animals are
    > > better camouflaged.
    > >
    > > Environmental condition 1 returns. Now spots are no longer the best
    > > camouflage again.
    > >
    > > Instead of completely eliminating all the genes for spots, they are just
    > > disabled with point mutations that prevent the genes from expressing
    > > themselves and the species returns to its grey state.
    > >
    > > Environmental condition 2 returns. Now spotting can reappear much more
    > > quickly because instead of having to re-evolve the entire spotting
    > > mechanism only the disabling point mutations have to be reversed.
    > >
    > > I don't think this is something Dawkins discusses, although I see
    > > in his ideas that would contradict the possibility of it
    > > happening. I did
    > > read 'The Selfish Gene' and I agree that it is quite a good book.
    > >
    > > Ray Recchia
    > >
    > >
    > > ===============================================================
    > > This was distributed via the memetics list associated with the
    > > Journal of Memetics - Evolutionary Models of Information Transmission
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    > > see:
    > >
    > ===============================================================
    > This was distributed via the memetics list associated with the
    > Journal of Memetics - Evolutionary Models of Information Transmission
    > For information about the journal and the list (e.g. unsubscribing)
    > see:

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