Mutation-biased adaptation in a protein NK model.
Evolutionary trends responsible for systematic differences in genome and proteome composition have been attributed to GC:AT mutation bias in the context of neutral evolution or to selection acting on genome composition. A possibility that has been ignored, presumably because it is part of neither the Modern Synthesis nor the Neutral Theory, is that mutation may impose a directional bias on adaptation. This possibility is explored here with simulations of the effect of a GC:AT bias on amino acid composition during adaptive walks on an abstract protein fitness landscape called an "NK" model. The results indicate that adaptation does not preclude mutation-biased evolution. In the complete absence of neutral evolution, a modest GC:AT bias of realistic magnitude can displace the trajectory of adaptation in a mutationally favored direction, to such a degree that amino acid composition is biased substantially and persistently. Thus, mutational explanations for evolved patterns need not presuppose neutral evolution.
Stoltzfus
Arlin
A
Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Gaithersburg, Maryland, USA. arlin.stoltzfus@nist.gov
D000222:Adaptation, Physiological; D000483:Alleles; D003198:Computer Simulation; D019143:Evolution, Molecular; D016678:Genome; D008957:Models, Genetic; D009154:Mutation; D011506:Proteins / Q000235:genetics*; D020543:Proteome; D012984:Software
D011506:Proteins; D020543:Proteome