Re: Ectothermy?

[TomHopp@aol.com]

In a message dated 9/3/98 1:27:38 PM, Thomas R. Holtz, Jr. wrote:

<<Yeah, Tom, I see what you mean. And what about the "hot blooded" tuna? A lot
of research there.>
    And, of course, endothermic plants like the skunk cabbage.  Oh, there you
go: endothermy must be basal to Eukaryota! :-)>

Being the second mentioned Tom above, I'd just like to add a note of agreement
with the first Tom. The evolution of something like endothermy is a tough nut
compared to say, the study of teeth, where function and evolutionary
derivation are relatively easy to infer from structure. Fossil evidence for
what you (larryf) are mooting is so rare (as in, mostly yet-to-be-discovered)
that I feel you may be frustrated in your efforts to gather relevant data on
ancient brooding endothermy, let alone convince any reasonably skeptical
scientist.  My comments have been intended to offer, not rejection of your
interesting concept, but alternatives and obscurity-plumbing questions. I
think you'll find some of them to be, simply, unknowable at this time. Don't
mean to discourage you, as much as to help you frame your own tough questions.
Sometimes, I think the better part of valor is to recognize the "You-can't-
get-there-from-here" qualities of some questions we all would love to know the
answers to.

    By the way -- to Tom Holtz -- wouldn't it be a shock if skunk cabbage DID
use a homologous uncoupling protein to generate its heat?
    That suggests another unknowable idea -- what if some form of endothermy
truly is very ancient?  Would there ever be reasons for endothermic creatures
to evolve TOWARD an ectothermic condition? I'll bet there are.  Maybe
endo/ectothermies are just options that come and go depending on lifestyle
requirements.
    Tom Hopp