Evolution of dosage compensation under sexual selection differs between X and Z chromosomes.
Evolution of dosage compensation under sexual selection differs between X and Z chromosomes.
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DOI：
10.1038/ncomms8720
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发表时间：
2015-07-27
影响因子：
16.6
通讯作者：
Mank JE
中科院分区：
文献类型：
--
作者：
Mullon C;Wright AE;Reuter M;Pomiankowski A;Mank JE
完全性染色体剂量补偿在XY物种中比在ZW物种中更常见。在这项研究中，我们使用群体遗传模型和鸡转录组来评估性别冲突是否可以解释这种差异。当突变效应在两性之间相互关联时，性别表达冲突是不可避免的，因为异型配型的补偿性突变导致同质配型的高表达。再加上雄性的选择更强，生殖变异更大，这导致Z的进化比X剂量补偿更慢，更不完整。使用表达方差作为选择强度的度量，我们发现，正如模型所预测的那样，鸡的剂量补偿在强选择偏向于雌性的基因中最为明显。我们的研究解释了ZW系统中弱剂量补偿的模式，并表明性选择在性染色体剂量补偿的形成中起主要作用。完全性染色体剂量补偿主要局限于雄性异配子物种，大多数雌性异配子物种表现为不完全剂量补偿。在这里，作者表明，基因表达的性别冲突与雄性的性选择相结合可以解释这种模式。
Complete sex chromosome dosage compensation has more often been observed in XY than ZW species. In this study, using a population genetic model and the chicken transcriptome, we assess whether sexual conflict can account for this difference. Sexual conflict over expression is inevitable when mutation effects are correlated across the sexes, as compensatory mutations in the heterogametic sex lead to hyperexpression in the homogametic sex. Coupled with stronger selection and greater reproductive variance in males, this results in slower and less complete evolution of Z compared with X dosage compensation. Using expression variance as a measure of selection strength, we find that, as predicted by the model, dosage compensation in the chicken is most pronounced in genes that are under strong selection biased towards females. Our study explains the pattern of weak dosage compensation in ZW systems, and suggests that sexual selection plays a major role in shaping sex chromosome dosage compensation. Complete sex chromosome dosage compensation is largely limited to male heterogametic species, with the majority of female heterogametic species displaying incomplete dosage compensation. Here, the authors show that sexual conflict over gene expression combined with sexual selection in males can explain this pattern.