Re: Insects mouths prepared in advance for flowers?

Stephen Jones (sejones@ibm.net)
Sun, 27 Jul 97 13:45:36 +0800

Brian

On Sun, 13 Jul 1997 00:15:40 -0400, Brian D Harper wrote:

RC>Stephen Jones quoted from the following by Massimo
>Piattelli-Palmarini (Principal Research Associate of the Center for
>Cognitive Science at MIT):
>
>"Inevitable Illusions: How Mistakes of Reason Rule Our Minds"
>(John Wiley & Sons: New York, 1994). Suffice it to remind the
>reader that insects had evolved at least ten elaborate forms of
>mouthpieces, uniquely "adapted" (one would say) to their feeding
>upon flowers, one hundred million years before there were any
>flowers on Earth. Try to explain that with the notion of adaptation.

BH>My initial reaction to this quote was that it sounded like
>something Gould might say. In other words, the intent of the
>author was to say that evolution is a very complex phenomena
>unlikely to be explained solely by adaptationism.

No doubt. He actually gives a plug for Gould:

"For a recent review of the success of a non-adaptationist theory of
evolution: Gould, S. J., and N. Eldredge. "Punctuated Equilibrium
Comes of Age, Nature 366:223-227 (1993)" (Piattelli-Palmarini M.,
"Inevitable Illusions: How Mistakes of Reason Rule Our Minds", 1994,
p236).

But if it cannot "be explained solely by adaptationism" maybe it can
be better explained by Intelligent Design?

BH>Be that as it may, I read the article in question
>tonight and could not find anywhere in it support
>for the claim above, i.e. that the mouthpieces are
>uniquely adapted to feeding on flowers. Perhaps I
>missed something.

Perhaps you did? The opening abstract expresses this sense
of surprise:

"The great radiation of modern insects began 245 million years ago
and was not accelerated by the expansion of angiosperms during the
Cretaceous period. The basic trophic machinery of insects was in
place nearly 100 million years before angiosperms appeared in the
fossil record." (Labandeira, C.C., & J.J. Sepkoski, "Insect Diversity
in the Fossil Record," Science, Vol. 261, 16 July 1993, p310)

The article points out that though there is "intricate ecological
coupling between the two groups" (ie. "insects" and "angiospermous
plants"), there is no fossil evidence that either has had any major
effect on the other:

"The extraordinary diversity of living insects has been attributed by
some workers to the diversity of angiospermous plants, which first
appear as fossils in the Lower Cretaceous. This notion is buttressed
by exhaustive examples of intricate ecological coupling between the
two groups, especially with regard to insect herbivory and
pollination" (p312)

But "the appearance and expansion of angiosperms had no influence
on insect familial diversification", and they call this "startling":

"The more startling interpretation that can be drawn from the data is
that the appearance and expansion of angiosperms had no influence
on insect familial diversification....Whenever plants originated, the
fossil data indicates that angiosperms experienced a tremendous
radiation in all geographic regions during the Albian and Cenomanian
stages of the Middle Cretaceous. However there is no signature of
this event in the family-level record of insects. Instead, the data in
Fig. 4 suggest that insect diversification actually slackened as
angiosperms radiated. Even if the drop in diversity below the
exponential trend during the Cretaceous were a result of a lack of
preservation or inadequate sampling of insect fossils, the fact remains
that the post-Paleozoic radiation of insect families commenced more
than 100 million years before angiosperms appeared in the fossil
record." (p313)

It was presumed that "angiosperms fueled the diversification of
insects":

"Part of the presumption that angiosperms fueled the diversification of
insects involves the inference that the diverse tissues and organs,
particularly leaves and flowers, of these advanced land plants
provided an expanded spectrum of ecological resources that could be
exploited by various guilds of herbivorous and pollinating insects"
(p313)

But, "virtually all major insect feeding types were in place considerably
before angiosperms":

"The geochronological distribution of mouthpart classes represented
among living insects (Fig. 5A) and their diversity through time (Fig.
5B) indicate that the number of feeding guilds among insects
expanded well before the appearance of fossil angiosperms. By the
Middle Jurassic, 65% (low estimate) to 88% (high estimate) of all
modern insect mouthpart classes were present, including several...that
are presently associated with flowering plants. After the expansion of
angiosperms, only 1 (low estimate) to 7 (high estimate) of the 34
mouthpart classes are known to have originated. However, these
have poor fossil records, and only one (siphonomandibulate) is
associated with flowering plants. Thus, by using mouthpart classes as
proxies for ecological disparity, we conclude that virtually all major
insect feeding types were in place considerably before angiosperms
became serious contenders in terrestrial ecosystems. Evidence from
the fossil record of vascular plant-insect interactions also supports
this inference." (pp313-314).

Therefore Piattelli-Palmarini concludes:

"Finally, the conceptions of biological evolution that we have today, with
the exception of those of a very few real specialists, are demonstrably so
naive and simple-minded that it is a safe bet that one day they will be a
source of considerable embarrassment. We shall all be embarrassed by
our sweeping statements in the years to come. Suffice it to remind the
reader that insects had evolved at least ten elaborate forms of
mouthpieces, uniquely "adapted" (one would say) to their feeding upon
flowers, one hundred million years before there were any flowers on
Earth." (Piattelli-Palmarini M., "Inevitable Illusions", 1994, p195)

Reinforcing that he is correct in this conclusion that this is a
"stunning" finding:

"The stunning story of insect mouthpieces having evolved long before
there were any flowers on Earth is told in: Labandeira, C. C., and J. J.
Sepkoski. "Insect Diversity in the Fossil Record," Science 261:310-
314 (1993)." (Piattelli-Palmarini M., "Inevitable Illusions", 1994,
p236)

is a favourable blurb on the back from Gould's pal Harvard zoology
professor Richard Lewontin:

"Fascinating and insightful...I cannot recall a book that has made me
think more about the nature of thinking." Richard C. Lewontin
Harvard University (Piattelli-Palmarini M., "Inevitable Illusions",
1994, back cover)

God bless.

Steve

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