title: Variation in promiscuity and sexual selection drives avian rate of Faster-Z evolution.
abstract: Higher rates of coding sequence evolution have been observed on the Z chromosome relative to the autosomes across a wide range of species. However, despite a considerable body of theory, we lack empirical evidence explaining variation in the strength of the Faster-Z Effect. To assess the magnitude and drivers of Faster-Z Evolution, we assembled six de novo transcriptomes, spanning 90 million years of avian evolution. Our analysis combines expression, sequence and polymorphism data with measures of sperm competition and promiscuity. In doing so, we present the first empirical evidence demonstrating the positive relationship between Faster-Z Effect and measures of promiscuity, and therefore variance in male mating success. Our results from multiple lines of evidence indicate that selection is less effective on the Z chromosome, particularly in promiscuous species, and that Faster-Z Evolution in birds is due primarily to genetic drift. Our results reveal the power of mating system and sexual selection in shaping broad patterns in genome evolution.
authors.affiliation: Department of Zoology, Edward Grey Institute, University of Oxford, Oxford, OX1 3PS, UK; Department of Genetics, Evolution and Environment, University College London, London, WC1E 6BT, UK.
authors.forename: Alison E
authors.initials: AE
authors.lastname: Wright
authors.forename: Peter W
authors.initials: PW
authors.lastname: Harrison
authors.forename: Fabian
authors.initials: F
authors.lastname: Zimmer
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Montgomery
authors.forename: Marie A
authors.initials: MA
authors.lastname: Pointer
authors.forename: Judith E
authors.initials: JE
authors.lastname: Mank
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001717:Birds / Q000235:genetics*; D005260:Female; D040961:Genetic Drift; D008297:Male; D052586:Mating Preference, Animal; D008957:Models, Genetic; D012641:Selection, Genetic; D012730:Sex Chromosomes / Q000235:genetics*; D059467:Transcriptome
keywords: Faster-Z evolution; effective population size; genetic drift; sexual selection