The effects of sex-biased gene expression and X-linkage on rates of adaptive protein sequence evolution in Drosophila.
The effects of sex-biased gene expression and X-linkage on rates of adaptive protein sequence evolution in Drosophila.
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DOI：
10.1098/rsbl.2015.0117
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发表时间：
2015-04
期刊：
影响因子：
3.3
通讯作者：
Charlesworth B
中科院分区：
文献类型：
--
作者：
Ávila V;Campos JL;Charlesworth B
与常染色体基因相比，x连锁基因的适应性进化速度更快可能是由新的隐性或部分隐性有利突变的固定引起的（faster - x效应）。这种效应在只影响男性适应性的突变中最大，而在只影响女性适应性的突变中则不存在。我们在黑腹果蝇中测试了这些预测，方法是使用具有不同性别偏倚表达水平的基因，并从多态性和分化数据中估计非同义突变的适应性进化程度。我们发现了Faster-X效应和男性偏倚基因表达的效应。没有证据表明这两种效应之间有很强的联系——适度的雄性偏倚基因表达增加了常染色体和X染色体的适应性进化速度，但非偏倚基因和雌性偏倚基因都出现了更快的X效应。基因重组的速度并没有影响Faster-X效应的大小，排除了它反映了x连锁基因较少的希尔-罗伯逊干扰的可能性。
A faster rate of adaptive evolution of X-linked genes compared with autosomal genes may be caused by the fixation of new recessive or partially recessive advantageous mutations (the Faster-X effect). This effect is expected to be largest for mutations that affect only male fitness and absent for mutations that affect only female fitness. We tested these predictions in Drosophila melanogaster by using genes with different levels of sex-biased expression and by estimating the extent of adaptive evolution of non-synonymous mutations from polymorphism and divergence data. We detected both a Faster-X effect and an effect of male-biased gene expression. There was no evidence for a strong association between the two effects—modest levels of male-biased gene expression increased the rate of adaptive evolution on both the autosomes and the X chromosome, but a Faster-X effect occurred for both unbiased genes and female-biased genes. The rate of genetic recombination did not influence the magnitude of the Faster-X effect, ruling out the possibility that it reflects less Hill–Robertson interference for X-linked genes.