slevesque writes:
No, but when discussing evolution, fixation is quite important. After all, we compare the fixed mutations between species to extrapolate common ancestors.
Wherever did you get such a strange idea? Ultimately every allele in a population's genome arose through mutation. Which alleles will you deem mutations and which not, since they're all ultimately mutations. And how would you ever identify which mutations were fixated (which means a gene with only a single allele) without sampling every individual of a population?
In the long run, only the fixed mutations will have a permanent impact. Temporary impacts from mutations that come and go through drift isn't relevant.
Two sentences, two misunderstandings.
First, fixated alleles do not have a permanent impact as they are as vulnerable to mutations as any other allele.
Second, non-fixated alleles do not have temporary impacts. Huge numbers of significant and influential alleles are not fixated.
Like I said before, you seem to be thinking of fixation as some kind of pinnacle of achievement for an allele, and that a gene can have no significant role if it isn't fixated. This is not true.
What is most important for the survival of species is variation. I bet the endangered Florida panther, which is well known for its lack of genetic diversity, has a much higher incidence of fixated alleles than non-endangered species. Fixation is only a good thing if you look at things from the allele's point of view. But it's the survival of the species that is of overwhelming importance, not the survival of alleles, and species survival depends upon variation, not fixation.
A population, or sub-population, evolves through fixation.
Uh, no.
--Percy
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