title: Constraint and turnover in sex-biased gene expression in the genus Drosophila.
abstract: Both genome content and deployment contribute to phenotypic differences between species. Sex is the most important difference between individuals in a species and has long been posited to be rapidly evolving. Indeed, in the Drosophila genus, traits such as sperm length, genitalia, and gonad size are the most obvious differences between species. Comparative analysis of sex-biased expression should deepen our understanding of the relationship between genome content and deployment during evolution. Using existing and newly assembled genomes, we designed species-specific microarrays to examine sex-biased expression of orthologues and species-restricted genes in D. melanogaster, D. simulans, D. yakuba, D. ananassae, D. pseudoobscura, D. virilis and D. mojavensis. We show that averaged sex-biased expression changes accumulate monotonically over time within the genus. However, different genes contribute to expression variance within species groups compared to between groups. We observed greater turnover of species-restricted genes with male-biased expression, indicating that gene formation and extinction may play a significant part in species differences. Genes with male-biased expression also show the greatest expression and DNA sequence divergence. This higher divergence and turnover of genes with male-biased expression may be due to high transcription rates in the male germline, greater functional pleiotropy of genes expressed in females, and/or sexual competition.
authors.affiliation: Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892, USA. yuzhang@mail.nih.gov
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: David
authors.initials: D
authors.lastname: Sturgill
authors.forename: Michael
authors.initials: M
authors.lastname: Parisi
authors.forename: Sudhir
authors.initials: S
authors.lastname: Kumar
authors.forename: Brian
authors.initials: B
authors.lastname: Oliver
mesh_terms: D000818:Animals; D004330:Drosophila / Q000145:classification / Q000235:genetics*; D019143:Evolution, Molecular; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics*; D049750:Genome, Insect / Q000235:genetics; D008297:Male; D012727:Sex Characteristics; D013045:Species Specificity