Re: What is an "active ectotherm"?

["Jonathan R. Wagner" <znc14@ttacs1.ttu.edu>]

At 01:30 AM 10/11/96 -0400, George O. wrote (quoting me):

>The fossil record is irrelevant here.

        No, it is what is relevant.  I argue that your transitional stages
in metabolic evolution need not be preserved at all, while you are
interpreting the enitre Dinosauria as a metabolically transitional group.

>I'm simply addressing the >number< of speciation events it would
>take to go from full ectothermy to full endothermy.

        I should like to hear your reasoning that it would require more than
one, please.

>To claim that full endothermy arose after only a few speciations is, I again
>assert, absurd.

        And I again ask for your reasoning.  Anyone can go around saying
various things are absurd, but, to be perfectly honest, I even take it with
a grain of salt when PhDs do this, so I'm just going to have to ask for more
than your authority.  You said it yourself, there are two choices: 1-10
speciations and more than 10 speciations.  I'm not saying I agree with this
assesment, but if you're going to prefer one over the other, I want to know
why.  This is the "back-up" I was talking about.

>Like lizards giving rise to gerbils.

        This is not reasoning.  A better simile would be "like lizards
giving rise to enothermic-homeothermic lizards"  Why is this absurd?

>To go from full ectothermy to full endothermy involves fine-tuning of
>innumerable physiological processes.  If you're going to make the
>extraordinary claim that this can occur within a few speciations, then it's
>up to you to provide the reasons for your claim.

        I'm going to assert that, within logical boundaries (mutation rate,
etc), evolution can do anything it darn well pleases (after all, even goats
can fly).  I really don't want to overstep the limitations of my experience
in biology, but I don't think it's going too far to suggest that there is a
lot of ectothermic thermoregulatory apparatus, and primitive auqatic
thermoregulatory aparatus, which can be dug up and exapted.  Evolution does
not work from whole cloth, and that just makes the stitching faster.
        And yes, people have brought up before that the rate of evolution is
pretty much independant of the other points I've made.  For all intents and
purposes, though, an animal will keep adapting until it doesn't need to any
more.  So now you're just going to have to show me that all of this could
not have happened over just a few speciations, if not only one.
        This is all in a modern approach to evolutionary biology.  I'm sure
that I have drastically oversimplified what is going on, but I still do not
see how this is such an "extraordinary claim", unless all you do is read old
texbooks about racial senescence and tail-dragging sluggard dinosaurs and
the liek.

>Sorry, I'm not referring to punctuated equilibria here.

        And I am.  Maybe that's why you don't seem to get my points.

>punctuated equilibria describes the apparent speed with which one species
>forms from another; it has little if anything to do with how long a species
>lasts or how many speciation events it takes to get from, say, an ectothermic
>animal to an endothermic animal.

        The paradigm of punctuated equilibrium has a lot to say about
gradualistic versus puncutated evolution in any form.  The work of many
scientists (what is referred to as the "modern synthesis", although IMHO it
doens't seem very synthesized :) ), including Gould et al., supports the
notion that evolution is a complex process involving reversals,
recapitulations, exaptations, all on a variable timescale.  It could be
summed up as "evolution does what it has to do in the time-scale it has to
do it in, within limitations which are far more complex than you might think.
        There are more thing in heaven and earth, George, than are dreamt of
in your philosophy.
        Or mine, for that matter.  I need to take a heat transfer course now...
 
>You show me the buck I've passed.

        No one was accusing you of anything...

        Wagner

+--------------------------------------------------------------------------+
| Jonathan R. Wagner                    "You can clade if you want to,     |
| Department of Geosciences              You can leave your friends behind |
| Texas Tech University                  Because your friends don't clade  |
| Lubbock, TX 79409                               and if they don't clade, |
|       *** wagner@ttu.edu ***           Then they're no friends of mine." |
|           Web Page:  http://faraday.clas.virginia.edu/~jrw6f             |
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