Mole rat metabolism (was "eaten words and food for thought")

["Ralph Miller III" <gbabcock@best.com>]

 Colette H. Adams <cadams@hh.gpz.org> wrote:

> Why should a house mouse and a warbler have similar
> metabolic rates?  One is forced to wonder whether there is something
> universal going on.  That's why I'm very interested in the mole rats.
> Obviously there has to be a period of intermediacy.  Are we catching mole
> rats in the process of evolving ectothermy?

My guess (and I do mean guess) is that the mole rat has already "achieved"
a state of ectothermy, and that this has come by paedomorphosis (the
retention of certain newborn *rodent* characteristics through adulthood,
i.e. hairlessness and the inability to generate sufficient heat
internally).  So in this case, I would imagine that this evolutionary
U-turn occurred not by the acquisition of novel physiological traits, but
rather, via the shedding of the unnecessary (and expensive) physiological
baggage of the endotherms (of which its direct rodent ancestors are
members) in favor of the simpler (and more energy efficient) metabolic
performance levels of its distant ancestors, as manifested in the condition
of the helpless newborn rodent (ontogeny recapitulating phylogeny, a rule
that sometimes applies, and sometimes doesn't).  In other words, "atavism."
 I leave it to the reader to decide if any of this conjecture could be
applied to a better understanding of non-avian dinosaur metabolism.  

-- Ralph Miller III     gbabcock@best.com

As punishment, I will be required to map the foregoing sentence structures,
and then eat my words.