Basic Body Design

Science's STKE  14 Feb 2006:
Vol. 2006, Issue 322, pp. tw61
DOI: 10.1126/stke.3222006tw61

Why have certain features of animal body plans, such as bilateral symmetry, been conserved since the early Cambrian period, whereas at the species level, there has been a continuous accumulation of changes? Davidson and Erwin propose that the genetic regulatory networks associated with development contain three components that differ in their evolutionary conservation. Evolutionarily inflexible subcircuits ("kernels") perform essential upstream functions in building given body parts, while other small subcircuits ("plug-ins") have been repeatedly coopted to diverse developmental purposes, leaving highly flexible, individual cis-regulatory linkages to regulate detailed phenotypic variation.

E. H. Davidson, D. H. Erwin, Gene regulatory networks and the evolution of animal body plans. Science 311, 796-800 (2006). [Abstract] [Full Text]