title: Symmetry breaking and adaptation: evidence from a 'toy model' of a virus.
abstract: We argue that an induced breaking of the genetic synonym symmetry due to the action of genetic operators such as mutation can enhance the adaptability of a species to changes in the environment. In the case of a virus, the claim is that the codon bias in the neutralization epitope improves the virus' ability to generate mutants that evade the induced immune response. We support our claim with a simple 'toy model' of a viral epitope evolving in competition with the immune system. The effective selective advantage of a higher mutability leads to a dominance of codons that favor non-synonymous mutations. As further evidence we present a simple model for a genetic regulatory network that leads to adaptive evolution in a population of giraffes by means of an induced symmetry breaking rather than through any direct selective advantage.
authors.affiliation: Facultad de Ingeniería, UNAM, DF, Mexico.
authors.forename: J M
authors.initials: JM
authors.lastname: Vargas
authors.forename: C R
authors.initials: CR
authors.lastname: Stephens
authors.forename: H
authors.initials: H
authors.lastname: Waelbroeck
authors.forename: F
authors.initials: F
authors.lastname: Zertuche
mesh_terms: D000222:Adaptation, Physiological; D000596:Amino Acids / Q000235:genetics; D000818:Animals; D002875:Chromosomes / Q000235:genetics*; D003062:Codon / Q000235:genetics; D003198:Computer Simulation; D019143:Evolution, Molecular; D017709:Fractals; D015870:Gene Expression; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D007107:Immune System / Q000502:physiology; D008957:Models, Genetic; D008962:Models, Theoretical; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D014780:Viruses / Q000235:genetics* / Q000276:immunology
chemical_list: D000596:Amino Acids; D003062:Codon