L.A. Moran (email@example.com) wrote: : In article <firstname.lastname@example.org>, : James Foster <email@example.com> wrote:
: More or less. I was trying to find out whether you attributed all of evolution : to natural selection. Apparently you do. I don't.
Yea, you're right. I overstated the case. Evolution can have many causes, and drift is certainly one.
: I believe that the current tree of life is largely the product of contingent : events (including genetic drift). This is not to deny that adaptation occurs : since there are many clear examples. I simply want to point out that many : of the historical events of the past may not be due to selection. I also : believe that most of evolution at the molecular level can be attributed to : the fixation of neutral alleles by drift. This has nothing to do with : natural selection and it accounts for much of the deversity that we see : in modern populations.
Drift is a source of change. Selection is NOT a source of change. So this is comparing apples to oranges, no? Selective pressure preserves preferentially some changes over others, whether those changes were caused by duplication, drift, re-combination, or whatever. Evolution is the coupled result of change AND selective pressure. -- James A. Foster email: firstname.lastname@example.org Laboratory for Applied Logic Dept. of Computer Science University of Idaho www: http://www.cs.uidaho.edu/~foster
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