title: Evolution of dosage compensation under sexual selection differs between X and Z chromosomes.
abstract: Complete sex chromosome dosage compensation has more often been observed in XY than ZW species. In this study, using a population genetic model and the chicken transcriptome, we assess whether sexual conflict can account for this difference. Sexual conflict over expression is inevitable when mutation effects are correlated across the sexes, as compensatory mutations in the heterogametic sex lead to hyperexpression in the homogametic sex. Coupled with stronger selection and greater reproductive variance in males, this results in slower and less complete evolution of Z compared with X dosage compensation. Using expression variance as a measure of selection strength, we find that, as predicted by the model, dosage compensation in the chicken is most pronounced in genes that are under strong selection biased towards females. Our study explains the pattern of weak dosage compensation in ZW systems, and suggests that sexual selection plays a major role in shaping sex chromosome dosage compensation.
authors.affiliation: 1] Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK [2] CoMPLEX, University College London, Gower Street, London WC1E 6BT, UK [3] Department of Ecology and Evolution, Biophore, University of Lausanne, Ch-1015 Lausanne, Switzerland.
authors.forename: Charles
authors.initials: C
authors.lastname: Mullon
authors.affiliation: 1] Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK [2] Department of Zoology, University of Oxford, The Tinbergen Building, South Parks Road, Oxford OX1 3PS, UK.
authors.forename: Alison E
authors.initials: AE
authors.lastname: Wright
authors.affiliation: Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: Max
authors.identifier: 0000000195540795
authors.initials: M
authors.lastname: Reuter
authors.affiliation: 1] Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK [2] CoMPLEX, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Pomiankowski
authors.affiliation: Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: Judith E
authors.initials: JE
authors.lastname: Mank
mesh_terms: D000818:Animals; D002645:Chickens; D004303:Dosage Compensation, Genetic / Q000235:genetics*; D019143:Evolution, Molecular; D005260:Female; D015870:Gene Expression; D020869:Gene Expression Profiling; D008297:Male; D012641:Selection, Genetic / Q000235:genetics*; D012730:Sex Chromosomes / Q000235:genetics*; D014960:X Chromosome; D049951:X Chromosome Inactivation