title: Sexually antagonistic selection on genetic variation underlying both male and female same-sex sexual behavior.
abstract: BACKGROUND
  Intralocus sexual conflict, arising from selection for different alleles at the same locus in males and females, imposes a constraint on sex-specific adaptation. Intralocus sexual conflict can be alleviated by the evolution of sex-limited genetic architectures and phenotypic expression, but pleiotropic constraints may hinder this process. Here, we explored putative intralocus sexual conflict and genetic (co)variance in a poorly understood behavior with near male-limited expression. Same-sex sexual behaviors (SSBs) generally do not conform to classic evolutionary models of adaptation but are common in male animals and have been hypothesized to result from perception errors and selection for high male mating rates. However, perspectives incorporating sex-specific selection on genes shared by males and females to explain the expression and evolution of SSBs have largely been neglected.
  
  
  RESULTS
  We performed two parallel sex-limited artificial selection experiments on SSB in male and female seed beetles, followed by sex-specific assays of locomotor activity and male sex recognition (two traits hypothesized to be functionally related to SSB) and adult reproductive success (allowing us to assess fitness consequences of genetic variance in SSB and its correlated components). Our experiments reveal both shared and sex-limited genetic variance for SSB. Strikingly, genetically correlated responses in locomotor activity and male sex-recognition were associated with sexually antagonistic fitness effects, but these effects differed qualitatively between male and female selection lines, implicating intralocus sexual conflict at both male- and female-specific genetic components underlying SSB.
  
  
  CONCLUSIONS
  Our study provides experimental support for the hypothesis that widespread pleiotropy generates pervasive intralocus sexual conflict governing the expression of SSBs, suggesting that SSB in one sex can occur due to the expression of genes that carry benefits in the other sex.
authors.affiliation: Animal Ecology, Department of Ecology and Genetics, Uppsala University, Evolutionary Biology Centre, Norbyvägen 18D, 75105, Uppsala, Sweden. david.berger@ebc.uu.se.
authors.forename: David
authors.initials: D
authors.lastname: Berger
authors.affiliation: Animal Ecology, Department of Ecology and Genetics, Uppsala University, Evolutionary Biology Centre, Norbyvägen 18D, 75105, Uppsala, Sweden.
authors.forename: Tao
authors.initials: T
authors.lastname: You
authors.affiliation: Animal Ecology, Department of Ecology and Genetics, Uppsala University, Evolutionary Biology Centre, Norbyvägen 18D, 75105, Uppsala, Sweden.
authors.forename: Maravillas R
authors.initials: MR
authors.lastname: Minano
authors.affiliation: Animal Ecology, Department of Ecology and Genetics, Uppsala University, Evolutionary Biology Centre, Norbyvägen 18D, 75105, Uppsala, Sweden.
authors.forename: Karl
authors.initials: K
authors.lastname: Grieshop
authors.affiliation: Animal Ecology, Department of Ecology and Genetics, Uppsala University, Evolutionary Biology Centre, Norbyvägen 18D, 75105, Uppsala, Sweden.
authors.forename: Martin I
authors.initials: MI
authors.lastname: Lind
authors.affiliation: Animal Ecology, Department of Ecology and Genetics, Uppsala University, Evolutionary Biology Centre, Norbyvägen 18D, 75105, Uppsala, Sweden.
authors.forename: Göran
authors.initials: G
authors.lastname: Arnqvist
authors.affiliation: Animal Ecology, Department of Ecology and Genetics, Uppsala University, Evolutionary Biology Centre, Norbyvägen 18D, 75105, Uppsala, Sweden.
authors.forename: Alexei A
authors.initials: AA
authors.lastname: Maklakov
mesh_terms: D000483:Alleles; D000818:Animals; D001517:Coleoptera / Q000235:genetics*; D019143:Evolution, Molecular; D005260:Female; D017344:Genes, Insect; D058685:Genetic Pleiotropy; D014644:Genetic Variation; D008297:Male; D010641:Phenotype; D012098:Reproduction; D012641:Selection, Genetic; D012727:Sex Characteristics; D012725:Sexual Behavior
keywords: Artificial selection; B-matrix; Behavioral syndrome; Genetic constraints; Intralocus sexual conflict; Mating strategy; Pleiotropy; Same-sex sexual behavior; Sexual antagonism; Sexual selection