CGC Bibliography Paper 5465

One small step for worms, one giant leap for "Bauplan?"

Fitch DHA, Sudhaus W

Medline:

12168615

Citation:

Evolution & Development 4: 243-246 2002

Type:

REVIEW

Genes:

Abstract:

A popular hypothesis about animal diversification is that unique changes occurred in the Precambrian or Cambrian (ca. 700-500 million of years [Myr] ago) to produce the distinctive features of all animal "Baupläne" ("body plans") and that such changes have not occurred since (Gould 1989:47). In contrast, we suggest that changes similar to the key innovations initiating the appearance of these distinctive features occur repeatedly during evolution. A major example is the "inversion" of the dorsoventral axis in the evolution of chordates (Arendt and Nübler-Jung 1994), initiated by a switch in mouth position from the neural to the abneural side. Here we note that similar changes in mouth position evolved < 50 Myr ago at least twice in a group of nematodes related to Caenorhabditis elegans. Because this means that such changes were not unique to the Cambrian, they can be studied by experimental approaches in closely related extant organisms. A direct consequence of this focus on studying elemental key changes is that "Bauplan" becomes a less useful concept for understanding how animal diversity