Re: BodyPlans
Thu, 20 Nov 1997 16:03:12 -0500 (EST)


In a message dated 11/16/97 6:42:34 PM, (Glenn Morton)

<<I need to get Arthur's book. Can you give me a full reference?>>

Here it is:

Wallace Arthur, *The Origin of Animal Body Plans* (Cambridge University
Press, 1997). Available at Cambridge University Press, 110 Midland Avenue,
Port Chester, NY 10573-4712, Phone: 800-872-7423. $69.

You wrote,

"And further I would disagree that bauplan in the sense that Gilbert used it
only applies to phyla and classes."

The definition of Bauplan was given by Valentine, not Gilbert. The term was
introduced by Joseph Henry Woodger in 1945. I have also seen the term
Unterbauplan used to refer to the taxonomic level of class. Rudolph Raff
defines a body plan as "a basic pattern of anatomical organization shared by
a group of animals--at the highest level of distinction, by a phylum." *The
Shape of Life* University of Chicago Press. 1996. pp. 30-31. He also wrote
that the *phylotypic stage* is when the body plan characteristic of its
phylum is blocked out relatively early in the development of any embryo.

John Gearhart and Marc Kirschner write that the "phylotypic body plan, [is]
that organization shared by all members of a phylum." *Cells, Embryos, and
Evolution* (Malden, MA: Blackwell Science, 1997). p. 296. That puts it at
the taxonomic level of phylum.

J. Z. Young, in his classic textbook on *The Life of Vertebrates* (Clarendon
Press, Oxford, 1981), has this to say about Bauplans,
"the basic plan of construction of an organism (Bauplan) limits the
possibilities of adaptational change. This is particularly obvious during
the early stages of development, *which are remarkably resistant to
evolutionary change*.
"Adaptational changes mostly come relatively late in ontogeny. Genes
controlling external features such as color can rapidly become incorporated
into the population. *Mutants affecting early embryological stages survive
only in the laboratory.* An organism must survive as best it can with its
given Bauplan." (p. 4). [My emphases.)

Body plans are clearly defined at "the highest level of distinction, by a
phylum". I hope you won't proceed to redefine what a body plan is just
because you disagree with the accepted definition.

Incidentally, I looked through Monroe Strickberger's *Encyclopedia of
Evolution* as well as Richard Milner's, (same title) and neither one has the
words *body plan* or *Bauplan* in their indexes. Maybe Strickberger's second
edition has something on them. Does anyone know?

Cheers, as always,