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Re: A Perspective on Cope's Rule
While the disparity in metabolism vs size, is greater
in automatic endotherms, I disagree that the small
animals = higher metabolisms statement doesn't hold
true for the rest of the animal world. The metabolism
of a little whiptail lizard, or anole, is noticeably
faster than that of a large iguana, or Komodo dragon.
That smaller reptiles have larger metabolic
fluctuations with temperature should be beside the
point, as the small critters usually work hard at
keeping their body temperatures high enough for their
metabolism to be at optimum efficiency.
I do not disagree that the "statement" may not hold for small vs large
reptiles, since your sample is still being limited to land vertebrates.
Further, I wonder if your "higher" metabolism in certain ectotherms have
more to do with surface area to volume ratios than internal generation of
heat and energy, as well as habitat.
Of course there are the weird ones, such as tuataras,
but they are the exceptions, rather than the rules.
I also believe that caecilians (Apoda) and worm lizards (Bipedidae,
Lacertilia) have slow metabolisms.