Siegal Mark L, Bergman Aviv
Department of Biological Sciences, and Center for Computational Genetics and Biological Modeling, Stanford University, Stanford, CA 94305-5020, USA.
Proc Natl Acad Sci U S A. 2002 Aug 6;99(16):10528-32. doi: 10.1073/pnas.102303999. Epub 2002 Jun 24.
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 regulators, 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 equilibrium 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 developmental-genetic processes and thus requires no explanation in terms of evolution to suppress phenotypic variation.
大多数物种保持着丰富的遗传变异，并经历一系列环境条件，但表型变异却很低。也就是说，发育对基因型和环境的变化具有稳健性。有人认为，这种被称为稳态化的稳健性是由于长期对最优表型的自然选择而进化而来的。我们表明，发育过程（这里建模为相互作用的转录调节因子网络）会限制遗传系统产生稳态化，即使没有朝着最优状态进行选择。以网络平衡状态对突变的不敏感性来衡量的稳态化程度，取决于网络的复杂性，使得连接性更高的网络进化得更具稳态化。我们认为，稳态化可能是复杂的发育 - 遗传过程的必然结果，因此无需从进化角度来解释以抑制表型变异。
