Re: Armadillos at the K/T!

["David Marjanovic" <david.marjanovic@gmx.at>]

----- Original Message -----
From: "John Bois" <jbois@umd5.umd.edu>
Sent: Wednesday, October 03, 2001 5:57 AM
Subject: Re: Armadillos at the K/T!


> > > > So why don't we see progress in evolution?
> > >
> > > Greater computational power in most vertebrates relative to Triassic
> > > species.
> >
> > Most vertebrates, you say? What about the 23,000 known recent species of
> > "fish" (or are these just "bony fish"?), the (some thousands... 4000?)
> > species of amphibians and the 6500 (IIRC) species of "reptiles"? Sure,
there
> > are almost 10,000 species of birds left, but that doesn't topple the
> > average.
>
> Yes, of course.  How about species with much greater computational power
> exist today--in terms of computational power, this is progress.

This is progress for the direct lineage of those species, not for any
others.

> > > Reproductive security and specialized nutritional
> > > structures in mammals vs. "stem reptiles".
> >
> > Nothing of that sort in most other amniotes. BTW, we don't know when
mammals
> > gave up laying and shelling eggs.
>
> There is a greater diversity of reproductive techniques today than in the
> Triassic--including marsupial, and placental strategies.

Greater diversity, yes (probably). Why is this progress?

> > > Ability to engage specialized
> > > vectors to carry your sperm in flowering plants.
> >
> > Even among flowering plants large groups (e. g. grasses, lots of trees)
have
> > reversed to engaging wind. I am allergic against several sorts of
angiosperm
> > pollen.
>
> Among flowering plants, options are greater for pollination--they can use
> vectors or wind, they can and have established intimate and complex
> symbioses with an enormous range of assistants.

The use of wind by angiosperms is a reversal. Is it progress?
What has happened to the idea that bennettitaleans had blossoms for insect
pollination?

> This is an increase in
> complexity and diversity of reproductive techniques, which, in the
> official court of progress, counts.

Official court of progress??????

> > > Independence from water in plants and animals.
> >
> > To varying degrees in whatever-you-mean-by-plants, not counting several
> > reversals, and not at all in lots of animals (even there with
reversals).
>
> No.  Animals and plants today enjoy a greater range of habitats relative
> to Cambrian times.  The ability to colonize land is, I'm told, seen as
> _very_ progressive in the court of progress.

So the evolution of whales etc. etc. is seen as _very_ regressive?
"Progress" is a very undefined and subjective concept in biology...

The evolution of endoparasitism can be regarded as a "key adaptation" in the
sense that endoparasitic clades spawn lots of species. It is always
associated with sometimes tremendous reductions of complexity. Just think of
Mesozoa or Myxozoa. Gould even thinks (just thinks, he has no numbers at
hand) that on the whole more clades have reduced complexity than increased
it; without endoparasitism it should be neutral, endoparasitism is a common
phenomenon that reduces complexity, and there is nothing recurrent that
increases it.

> > Yes, the range of complexity or whatever covered by
> > organisms has increased, but there is no progress when you closely look
at
> > it.

To be more precise: there is only progress, whatever that is, for some short
lineage segments, progress is nothing general in evolution. (Ah,
*Nannippus*... the secondarily small horse with higher tooth crowns than
*Equus*...)

> Of course "progress" only has meaning to humans.  I am happy to accept
> your words: the range of complexity covered by organisms has increased...
> And now, paraphrasing our original argument: species that can't cope with
> the range of complexity are gone.

OK, but many species that could cope and have coped are gone, too.

> >         You have limited yourself to vertebrates. So you can
unconciously
> > overlook most life -- most of which is microscopic, and on the whole
devoid
> > of progress.
>
> Whatever you want to call it, when organisms started to live symbiotically
> and create the first eukaryotic cells, this was a great leap forward in
> increasing complexity.

For their ancestors. Not for anything else. *Archaeoglobus fulgidus* doesn't
care.