Mutations

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DNAunion: This evolution (changes in allelic frequencies in a population) didn't involve any new mutations, but rather simply changes in selection based on differing fitnesses of preexisting phenotypes/genotypes under different environmental conditions.

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CrashFrog: But where did the different genotypes come from? Mutations, presumably, right?

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In that case how is it inaccurate to say that mutation was the underlying source of variety?

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Please point out where I stated, or even implied, that mutations weren't the source of the underlying VARIETY?[This message has been edited by DNAunion, 03-08-2004]

I guess I misunderstood, but when somebody quotes a statement, and then says "I disagree", I take it to mean that they're disagreeing with that statement.Sylas's statement was that mutation was the underlying source of variety. You appeared to disagree with that. If that's not what you meant, then you should have been more specific about exactly what part of Sylas's statement you were disagreeing with.Actually, I take that back. You quoted this:

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So in a sense, all evolution is based on mutation; since this is the underlying source of variety.

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and disagreed with it. Now that's more or less two statements: "In a sense, all evolution is based on mutation" and "mutation is the underlying source of variety." If you don't disagree with the second statement, then perhaps you shouldn't have appeared to disagree with Sylas's whole statement.Do you see my confusion? What exactly do you disagree with?[This message has been edited by crashfrog, 03-08-2004]

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Crashfrog: You quoted this:

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So in a sense, all evolution is based on mutation; since this is the underlying source of variety.
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and disagreed with it. Now that's more or less two statements: "In a sense, all evolution is based on mutation" and "mutation is the underlying source of variety." If you don't disagree with the second statement, then perhaps you shouldn't have appeared to disagree with Sylas's whole statement.

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Do you see my confusion? What exactly do you disagree with?

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Several things, of which I pointed out just one.Others had already pointed out that evolution can be based on other mechanisms, such as symbiosis.I believe someone also mentioned that evolution can occur by the "shuffling" of PREEXISTING alleles in a population due to genetic recombination.And I added that even though PREEXISTING VARIETY for a given trait in a population is generated at some unknown point in the past by one or more mutations, EVOLUTION can still occur based SOLEY ON NATURAL SELECTION (i.e., without being based on mutations - of course, since the phrase based on hasn’t been properly defined, there’s an inherent problem here).In fact, any population that is not in Hardy-Weinberg equilibrium is evolving, and there are about half a dozen mechansims other than mutations that can cause that.[This message has been edited by DNAunion, 03-08-2004]

Ok, I see now. Thanks.