%0 Journal Article %J Evolution %D 2006 %T Self-imposed silence: parental antagonism and the evolution of X-chromosome inactivation %A Haig, D. %K *Biological Evolution %K *Models, Biological %K *X Chromosome Inactivation %K Animals %K Dosage Compensation, Genetic %K Female %K Genes, X-Linked %K Male %X

A model is proposed for the evolution of X-chromosome inactivation (XCI) in which natural selection initially favors the silencing of paternally derived alleles of X-linked demand inhibitors. The compensatory upregulation of maternally derived alleles establishes a requirement for monoallelic expression in females. For this reason, XCI is self-reinforcing once established. However, inactivation of a particular X chromosome is not. Random XCI (rXCI) is favored over paternal XCI because rXCI reduces the costs of functional hemizygosity in females. Once present, rXCI favors the evolution of locus-by-locus imprinting of X-linked loci, which creates an evolutionary dynamic in which different chromosomes compete to remain active.

%B Evolution %V 60 %P 440-7 %8 Mar %@ 0014-3820 (Print)0014-3820 (Linking) %G eng %M 16637489 %! Evolution; international journal of organic evolutionEvolution; international journal of organic evolution