David Campbell wrote:
> > 1. A mechanism that can make substantial genetic changes in step wise fashion.
> > 2. The existence of a gene trajectory path from animal A to animal B with
> >each change being large and benficial enough to modify reproduction rates for
> >the animal with the genetic benefits.
>
> As long as accumulated mutations do not decrease the reproductive success
> so much as to cause it to die out, they can persist. This depends strongly
> on how tough the selective pressure is. If everything is easy,
> disadvantageous mutants can survive because there is little pressure. If
> the environment is so bad that everyone is in trouble, disadvantageous
> mutants may be able to survive because they are not competing against other
> individuals but are rather matched against the environment. This fits the
> pattern of gradual and punctuated patterns in the fossil record fairly
> well, to the extent that it has been examined. Times with low competition
> (such as just after a mass extinction) or very stable conditions tend to
> show rapid evolutionary radiation or gradual change. Times with moderate
> environmental variation tend to show stasis punctuated by rapid shifts.
>
> > 3. A quickly acting mechanism to make this happen which is triggered by
> >something to be identified because the fossil evidence is for stasis with
> >punctuated and rapid changes.
>
> One rapid mechanism for genetic change comes from the role of heat-shock
> proteins. Normally, they stabilize other proteins. However, they transfer
> over to emergency use in times of severe cellular stress, such as heat
> shock. When they abandon their normal stabilizing function, mutations in
> those proteins that had been covered by the work of the heat-shock proteins
> may come into play and be selected for or against.
*************
David
This is speculation not explanation. Where is the evidence that at a time of severe
stress for whatever the cause that a blind animal suddenly developes the ability to
see by this mechanism? Certainly if you believe as I do that these rapid periods of
invention occured you must postulate a means to make it happen. However, I still do
not see a viable mechanism. If you believe in this above postulate, may I ecourage
you to take some fruit flies (take a large population and the little animals breed
rapidly) and get some experimental evidence for inventive genetics (sorry, bigger
wings or different color will not do). I want to see some new body feature of
import. This is not a hard experiment and the numbers of generations and population
levels should be adequate.
Bert M.
>
>
> David C.
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