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Waddington's canalization revisited: Developmental stability and evolution

Summary: Waddington's canalization revisited: Developmental
stability and evolution
Mark L. Siegal* and Aviv Bergman*
*Department of Biological Sciences, and Center for Computational Genetics and Biological Modeling, Stanford University, Stanford, CA 94305-5020
Communicated by Bruce S. Baker, Stanford University, Stanford, CA, May 20, 2002 (received for review April 8, 2002)
Most species maintain abundant genetic variation and experience
a range of environmental conditions, yet phenotypic variation is
low. That is, development is robust to changes in genotype and
environment. It has been claimed that this robustness, termed
canalization, evolves because of long-term natural selection for
optimal phenotypes. We show that the developmental process,
here modeled as a network of interacting transcriptional regula-
tors, constrains the genetic system to produce canalization, even
without selection toward an optimum. The extent of canalization,
measured as the insensitivity to mutation of a network's equilib-
rium state, depends on the complexity of the network, such that
more highly connected networks evolve to be more canalized.
We argue that canalization may be an inevitable consequence
of complex developmental­genetic processes and thus requires
no explanation in terms of evolution to suppress phenotypic


Source: Azevedo, Ricardo - Department of Biology and Biochemistry, University of Houston
Bergman, Aviv - Department of Systems and Computational Biology, Albert Einstein College of Medicine, Yeshiva University


Collections: Biology and Medicine; Environmental Sciences and Ecology