Male-driven evolution of DNA sequences in birds
Male-driven evolution of DNA sequences in birds
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DOI：
10.1038/ng1097-182
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发表时间：
1997-10-01
期刊：
影响因子：
30.8
通讯作者：
Fridolfsson, AK
中科院分区：
文献类型：
--
作者：
Ellegren, H;Fridolfsson, AK
假设新的突变主要发生在 DNA 复制过程中，哺乳动物的序列进化被视为“雄性驱动”（参考文献 1），因为精子发生过程中的细胞分裂比卵子发生过程中的细胞分裂要多得多。这一观点的分子支持是通过观察灵长类和啮齿类动物 (2-4) 的 Y 染色体上的基因取代率高于 X 染色体上的基因获得的，这些物种是具有雄性异配性的物种，但尚未通过具有雌性异配性的生物体的相互分析得到证实。最近的建议是，X 染色体突变率的内在降低可能与先前比较中的雄性效应相混淆(5)，而灵长类 Y 染色体 (6-8) 上低水平多态性的矛盾发现表明，需要重新审视雄性偏向突变率的想法。我们分析了存在于鸟类 Z 和 W 性染色体上的 CHD 基因的分子进化。 Z 染色体上同义位置以及内含子 DNA 的替换率明显高于女性特有的 W 染色体，估计突变率 (alpha(m)) 中男性与女性的偏差为 3.9-6.5。因此，鸟类的进化似乎是由雄性驱动的——这种情况支持分子进化的中性模型。
Assuming that new mutations arise mainly during DNA replication, sequence evolution in mammals has been seen as 'male driven' (ref. 1) because of the many more cell divisions in spermatogenesis than in oogenesis. Molecular support for this idea has been obtained from the observation of higher substitution rates in genes on the Y than on the X chromosome of primates and rodents(2-4), which are species with male heterogamety, but has not been confirmed by the reciprocal analysis of organisms with female heterogamety. The recent suggestion that an intrinsic reduction in the X-chromosome mutation rate may be confounded with male effects in previous comparisons(5), and the paradoxical finding of low levels of polymorphism on the primate Y chromosome(6-8) indicate that the idea of male-biased mutation rate needs to be re-examined. We have analysed the molecular evolution of the gene CHD, which is present on the Z and W sex chromosomes of birds. The substitution rate at synonymous positions, as well as in intron DNA, was considerably higher on the Z chromosome than on the female-specific W chromosome, with an estimated male-to-female bias in mutation rate (alpha(m)) of 3.9-6.5. Thus, evolution appears to be male driven in birds-a situation that supports a neutral model of molecular evolution.