Tuesday, February 14, 2006
Gene Regulatory Networks and the Evolution of Animal Body Plans
Development of the animal body plan is controlled by large gene regulatory networks (GRNs), and hence evolution of body plans must depend upon change in the architecture of developmental GRNs. However, these networks are composed of diverse components that evolve at different rates and in different ways. Because of the hierarchical organization of developmental GRNs, some kinds of change affect terminal properties of the body plan such as occur in speciation, whereas others affect major aspects of body plan morphology. A notable feature of the paleontological record of animal evolution is the establishment by the Early Cambrian of virtually all phylum-level body plans. We identify a class of GRN component, the 'kernels' of the network, which, because of their developmental role and their particular internal structure, are most impervious to change. Conservation of phyletic body plans may have been due to the retention since pre-Cambrian time of GRN kernels, which underlie development of major body parts.
Reprints available from Eric Davidson at the email address on the following link (or contact firstname.lastname@example.org):
Model of an Internal Evolutionary Mechanism
Show me five examples where gene duplication took place and then one of these two genes "evolved" into a phenotype to create a completely new species. Amphibian fins became mammal hands ..., epigenetically. I say, "Not!"
Now with this idea in mind, let's find just one of the many different and diparate configurations, and then create one kernal to then say we created life in a lab; a new life that has never before existed until some researchers put it together in a laboratory ... somewhere in the West.
Either, "Wow," or the alarm clock is eventually going to go off and I'll wake up.
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