Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa 52242
Department of Biology, University of Iowa, Iowa 52242.
Genetics. 2018 Oct;210(2):703-718. doi: 10.1534/genetics.118.301229. Epub 2018 Aug 21.
Interactions among divergent elements of transcriptional networks from different species can lead to misexpression in hybrids through regulatory incompatibilities, some with the potential to generate sterility. While the possible contribution of faster-male evolution to this misexpression has been explored, the role of the hemizygous chromosome (, the dominance theory for transcriptomes) remains yet to be determined. Here, we study genome-wide patterns of gene expression in females and males of , and their hybrids. We used attached-X stocks to specifically test the dominance theory, and we uncovered a significant contribution of recessive alleles on the chromosome to hybrid misexpression. Our analyses also suggest a contribution of weakly deleterious regulatory mutations to gene expression divergence in genes with sex-biased expression, but only in the sex toward which the expression is biased (, genes with female-biased expression when analyzed in females). In the opposite sex, we found stronger selective constraints on gene expression divergence. Although genes with a high degree of male-biased expression show a clear signal of faster-X evolution of gene expression, we also detected slower-X evolution in other gene classes (, female-biased genes). This slower-X effect is mediated by significant decreases in - and -regulatory divergence. The distinct behavior of X-linked genes with a high degree of male-biased expression is consistent with these genes experiencing a higher incidence of positively selected regulatory mutations than their autosomal counterparts.
不同物种转录网络中不同成分之间的相互作用可能导致杂种中基因表达的错误，这可能是由于调控不兼容，其中一些可能导致不育。虽然已经探讨了雄性进化更快对这种错误表达的可能贡献，但杂种中半合子染色体（转录组的显性理论）的作用仍有待确定。在这里，我们研究了 、 及其杂种雌性和雄性中的全基因组基因表达模式。我们使用附着 X 品系来专门测试显性理论，结果发现 染色体上的隐性等位基因对杂种的错误表达有显著贡献。我们的分析还表明，在具有性别偏向表达的基因中，弱有害调控突变对基因表达分化有一定的贡献，但仅在表达偏向性的性别中（即当在雌性中分析时具有雌性偏向表达的基因）。在相反的性别中，我们发现对基因表达分化的选择约束更强。虽然具有高度雄性偏向表达的基因显示出 X 染色体上基因表达快速进化的明显信号，但我们也检测到其他基因类别的 X 染色体进化较慢（即，在雌性中分析时具有雌性偏向表达的基因）。这种较慢的 X 效应是由 - 和 - 调控分化的显著减少介导的。具有高度雄性偏向表达的 X 连锁基因的不同行为与这些基因经历更多的正选择调控突变有关，而不是它们的常染色体对应物。
