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posted 12. December 2001 18:37
The contents of this paper are from a poster presented by Paul Nelson and Jonathan Wells at a conference on "The Developmental Basis of Evolutionary Change," held at the University of Chicago, Oct. 25-27, 2001.
Searching for Deep Variation in the Model Systems of Evo-Devo
by Paul Nelson and Jonathan Wells
pnelson2@ix.netcom.com
jonwells2001@attbi.com
ABSTRACT—Evolution by natural selection requires variations that (a) exhibit fitness differences, and (b) are heritable. We use these criteria to examine what McDonald called a "great Darwinian paradox," namely, that there is little evidence for relevant variation at "those regulatory loci set deep with the control network" (1983, 92-3) of metazoan ontogenies. Currently, the absence of heritable variation in what Wimsatt calls the "deeply-entrenched" features of ontogeny has led many investigators to argue that profound temporal asymmetries exist in evolutionary history; in short, things were different in the pre-Cambrian. Yet it is unclear how ontogenetic architectures early in metazoan history could have differed fundamentally from present-day systems. We have commenced a survey of the literature of the principal model systems of evo-devo, as well as lesser-known systems, looking for evidence of heritable mutations in such features as cleavage patterns, axis specification, or modes of gastrulation. The continued absence of such evidence suggests that it may be time to re-examine basic assumptions.
To read the entire paper, please click here
[ 05 May 2002, 15:53: Message edited by: Moderator ]
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