title: Sexually antagonistic epigenetic marks that canalize sexually dimorphic development.
abstract: The sexes share the same autosomal genomes, yet sexual dimorphism is common due to sex-specific gene expression. When present, XX and XY karyotypes trigger alternate regulatory cascades that determine sex-specific gene expression profiles. In mammals, secretion of testosterone (T) by the testes during foetal development is the master switch influencing the gene expression pathways (male vs. female) that will be followed, but many genes have sex-specific expression prior to T secretion. Environmental factors, like endocrine disruptors and mimics, can interfere with sexual development. However, sex-specific ontogeny can be canalized by the production of epigenetic marks (epimarks) generated during early ontogeny that increase sensitivity of XY embryos to T and decrease sensitivity of XX embryos. Here, we integrate and synthesize the evidence indicating that canalizing epimarks are produced during early ontogeny. We will also describe the evidence that such epimarks sometimes carry over across generations and produce mosaicism in which some traits are discordant with the gonad. Such carryover epimarks are sexually antagonistic because they benefit the individual in which they were formed (via canalization) but harm opposite-sex offspring when they fail to erase across generations and produce gonad-trait discordances. SA-epimarks have the potential to: i) magnify phenotypic variation for many sexually selected traits, ii) generate overlap along many dimensions of the masculinity/femininity spectrum, and iii) influence medically important gonad-trait discordances like cryptorchidism, hypospadias and idiopathic hirsutism.
authors.affiliation: Department of Ecology, Evolution & Marine Biology, University of California, Santa Barbara, CA, 93106, USA.
authors.forename: William R
authors.initials: WR
authors.lastname: Rice
authors.affiliation: IFM Biology, AVIAN Behavioural Genomics and Physiology Group, Linköping University, SE-581 83, Linköping, Sweden.
authors.forename: Urban
authors.initials: U
authors.lastname: Friberg
authors.affiliation: Department of Ecology and Evolutionary Biology and Department of Mathematics, National Institute for Mathematical and Biological Synthesis, University of Tennessee, Knoxville, TN, 37996, USA.
authors.forename: Sergey
authors.initials: S
authors.lastname: Gavrilets
mesh_terms: D000818:Animals; D044127:Epigenesis, Genetic; D005260:Female; D008297:Male; D008322:Mammals / Q000235:genetics* / Q000254:growth & development; D009154:Mutation; D012727:Sex Characteristics
keywords: canalization; epigenetics; gonad-trait discordance; sex-specific epimarks; sexual conflict; sexual dimorphism; transgenerational epigenetics