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Wikipedia explanation of Neutral Theory: "most evolutionary changes and most of the variation within and between species is not caused by natural selection but

Wikipedia explanation of Neutral Theory: "most evolutionary changes and most of the variation within and between species is not caused by natural selection but by genetic drift of mutant alleles that are neutral. A neutral mutation is one that does not affect an organism's ability to survive and reproduce. The neutral theory allows for the possibility that most mutations are deleterious, but holds that because these are rapidly removed by natural selection, they do not make significant contributions to variation within and between species at the molecular level. Mutations that are not deleterious are assumed to be mostly neutral rather than beneficial. In addition to assuming the primacy of neutral mutations, the theory also assumes that the fate of neutral mutations is determined by the sampling processes described by specific models of random genetic drift." https://en.wikipedia.org/wiki/Neutral_theory_of_molecular_evolution https://en.wikipedia.org/wiki/Neutral_theory_of_molecular_ev...

nwatson 8y ago
The article is long and I don't have time to read this, but the article seems to imply that "neutral" mutations aren't driving the split between species. I would have thought though that for a given species in a given timeframe facing many-dimensional gradient pressure for "fitness" that: - few outlandishly positive mutations would crop up - natural selection would quickly weed out deleterious mutations (the article addresses this) - over time a very large number of "neutral" mutations and therefore neutral variations within the species would accumulate since their effect is completely orthogonal to the current pressures the species faces (the article implies that this is not relevant for evolution, however I think it would be extremely relevant as I describe following ...) The "neutral" mutations would form the "library" of variations that would become relevant at a LATER time when conditions change for a subset of the population of the species and a different gradient becomes relevant. Some of the previously neutral changes would become deleterious in the new setting, while others would provide outright advantages. It is these surviving mutations that would give the sub-group of the original species its new identity. Conclusion: I would think that the mutations that drive the new species' initial offshoot would come from the inherent variation built up by the prior neutral mutations ... i.e., the evolution was already primed by the prior library of previously neutral mutations and not something that happened solely after isolation and changes in conditions. EDIT: wording

nwatson 8y ago

The article is long and I don't have time to read this, but the article seems to imply that "neutral" mutations aren't driving the split between species. I would have thought though that for a given species in a given timeframe facing many-dimensional gradient pressure for "fitness" that: - few outlandishly positive mutations would crop up - natural selection would quickly weed out deleterious mutations (the article addresses this) - over time a very large number of "neutral" mutations and therefore neutral variations within the species would accumulate since their effect is completely orthogonal to the current pressures the species faces (the article implies that this is not relevant for evolution, however I think it would be extremely relevant as I describe following ...) The "neutral" mutations would form the "library" of variations that would become relevant at a LATER time when conditions change for a subset of the population of the species and a different gradient becomes relevant. Some of the previously neutral changes would become deleterious in the new setting, while others would provide outright advantages. It is these surviving mutations that would give the sub-group of the original species its new identity. Conclusion: I would think that the mutations that drive the new species' initial offshoot would come from the inherent variation built up by the prior neutral mutations ... i.e., the evolution was already primed by the prior library of previously neutral mutations and not something that happened solely after isolation and changes in conditions. EDIT: wording