Department of Molecular Biology and Genetics, Cornell University, USA.
Genome Biol Evol. 2011;3:151-5. doi: 10.1093/gbe/evr004. Epub 2011 Feb 2.
Genome-wide mRNA transcription profiles reveal widespread molecular sexual dimorphism or "sex-biased" gene expression, yet the relationship between molecular and phenotypic sexual dimorphism remains unclear. A major unresolved question is whether sex-biased genes typically perform male- and female-specific functions (whether these genes have sex-biased phenotypic or fitness consequences) or have similar functional importance for both sexes. To elucidate the relationship between sex-biased transcription and sex-biased fitness consequences, we analyzed a large data set of lethal, visible, and sterile mutations that have been mapped to the Drosophila melanogaster genome. The data permitted us to classify genes according to their sex-specific mutational effects and to infer the relationship between sex-biased transcription level and sex-specific fitness consequences. We find that mutations in female-biased genes are (on average) more deleterious to females than to males and that mutations in male-biased genes tend to be more deleterious to males than to females. Nevertheless, mutations in most sex-biased genes have similar phenotypic consequences for both sexes, which suggests that sex-biased transcription is not necessarily associated with functional genetic differentiation between males and females. These results have interesting implications for the evolution of sexual dimorphism and sex-specific adaptation.
全基因组 mRNA 转录谱揭示了广泛的分子性别二态性或“性别偏向”基因表达，但分子和表型性别二态性之间的关系仍不清楚。一个未解决的主要问题是，性别偏向基因是否通常具有雄性和雌性特定的功能（这些基因是否具有性别偏向的表型或适合度后果），或者对两性具有相似的功能重要性。为了阐明性别偏向转录与性别偏向适合度后果之间的关系，我们分析了大量已映射到黑腹果蝇基因组的致死、可见和不育突变的数据集。这些数据使我们能够根据基因的性别特异性突变效应对其进行分类，并推断性别偏向转录水平与性别特异性适合度后果之间的关系。我们发现，雌性偏向基因的突变（平均而言）对雌性的危害性大于对雄性的危害性，而雄性偏向基因的突变则往往对雄性的危害性大于对雌性的危害性。然而，大多数性别偏向基因的突变对两性都有相似的表型后果，这表明性别偏向转录不一定与雄性和雌性之间的功能遗传分化有关。这些结果对性二态性和性别特异性适应的进化具有有趣的意义。
