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Re: FW: A Perspective on Cope's Rule

I've heard this said a few times: Small mammals have a more rapid
metabolism, therefore they generate more free radicals, therefore there is
more oxidative damage to the DNA, therefore the DNA accumulates more
mutations. However, the genomic DNA is contained within the nucleus, and is
endowed with its own suite of DNA-repair enzymes. So, I'm not at all sure
that higher metabolism = higher mutation rate is actually true (apart from
mitochondrial DNA, perhaps).

The nucleus has many large pores, and most of the radicals can diffuse through cell membranes anyway (assuming they don't react with it). DNA repair enzymes are present in large animals just as well, so I don't think they matter all that much for this...

Do you have references?

On this list an article was mentioned that focused on the effect of the above on molecular divergence date estimates. I remember you tried to dampen my praise. :o)

Also, the small animals = higher metabolism thing really only holds for endotherms.

Sorry, that's most probably true.