Trade-off Between Selection for Dosage Compensation and Masculinization on the Avian Z Chromosome
Trade-off Between Selection for Dosage Compensation and Masculinization on the Avian Z Chromosome
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DOI：
10.1534/genetics.112.145102
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发表时间：
2012-12
期刊：
影响因子：
3.3
通讯作者：
Alison E. Wright;H. Moghadam;J. Mank
中科院分区：
文献类型：
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作者：
Alison E. Wright;H. Moghadam;J. Mank
重组抑制后，性别限制染色体上的基因表达水平下降，这可能导致选择异配子性别中的剂量补偿，以重新平衡X或Z染色体的平均表达与平均常染色体表达。与此同时，由于男性和女性的遗传模式不平等，性染色体受到不平衡的性别特异性选择的影响，与基因组的其余部分相比，这导致了性别偏向基因的非随机分布。这两种力量相互作用，目前还不清楚每一种力量的相对重要性。原鸡Z染色体提供了一个有用的机会，研究性别特异性选择和剂量补偿之间的重要性和权衡，在塑造基因组的进化，因为它显示不完全的剂量补偿，也是目前的两倍，往往在男性比女性，因此预计将丰富男性偏向的基因。在这里，我们完善了我们对鸟类Z染色体进化的理解，并表明在超过1.3亿年的时间里，染色体上形成了多个层次。然后，我们使用这一进化历史来研究性染色体剂量补偿选择的相对强度与雄性化选择对基因表达的累积效应。我们发现，男性偏向的表达随着时间的推移而增加，这表明在塑造Z染色体基因表达方面，剂量补偿的选择比男性化选择相对不那么重要。
Following the suppression of recombination, gene expression levels decline on the sex-limited chromosome, and this can lead to selection for dosage compensation in the heterogametic sex to rebalance average expression from the X or Z chromosome with average autosomal expression. At the same time, due to their unequal pattern of inheritance in males and females, the sex chromosomes are subject to unbalanced sex-specific selection, which contributes to a nonrandom distribution of sex-biased genes compared to the remainder of the genome. These two forces act against each other, and the relative importance of each is currently unclear. The Gallus gallus Z chromosome provides a useful opportunity to study the importance and trade-offs between sex-specific selection and dosage compensation in shaping the evolution of the genome as it shows incomplete dosage compensation and is also present twice as often in males than females, and therefore predicted to be enriched for male-biased genes. Here, we refine our understanding of the evolution of the avian Z chromosome, and show that multiple strata formed across the chromosome over ∼130 million years. We then use this evolutionary history to examine the relative strength of selection for sex chromosome dosage compensation vs. the cumulative effects of masculinizing selection on gene expression. We find that male-biased expression increases over time, indicating that selection for dosage compensation is relatively less important than masculinizing selection in shaping Z chromosome gene expression.