I return to the point that DNA does not survive more than a few thousand years. And yet you are talking about deep time.
Precisely. The “deep time” that gpuccio and others are referring to is based on phylogenies which are themselves based on the theory of evolution. It is natural selection that is preserving these sequences through deep time.
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Are you claiming that todays shark is not an ancestor of sharks 400 million years ago?
Not necessarily.
No, it’s being measured using comparative gene sequences.
Yes! I do however think modern sharks are descended from ancestors that look very much like the shark fossils we find in Devonian strata.
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So then would you agree that modern sharks DNA has had 400 million years to mutate?
OK, so you take sequence A and compare it to sequence B. Presumably it will be identical, entirely different or any possibility in between. Correct?
If it isn’t natural selection that is preserving those sequences then the entire method for measuring functional information breaks down.
They are also using phylogenies to determine the amount of time a specific residue has been around. Those phylogenies are based on evolution.
Remember the niche, Bill. If the niche is stable, purifying selection will keep a population from diversifying.
If a mutation stops a zygote from forming that is that natural selection?
Too much preservation to explain it by the niche.
Of course. Evolution depends on differential reproduction. The three important processes are adaptation, speciation and extinction.
Why do you assert that? Any reason to do so? Stable environments can exist over a long time. Especially marine environments
Thank you. I agree that we are seeing aggressive purifying selection as these are generally complex proteins that interface with other proteins and have little tolerance for mutation.
Yes. Lethal mutations are a perfect example of natural selection taking place.
But gpuccio’s method, Bill! We are wandering off the subject. How does gpuccio’s method work?
400 million years is a long time.
It really depends on the protein. For example, there are thousands of alleles in the human population for some of the HLA proteins.
I have explained it. Please re read the thread.