Selection on amino acid substitutions in Arabidopsis
Selection on amino acid substitutions in Arabidopsis
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DOI：
10.1093/molbev/msn079
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发表时间：
2008-07-01
影响因子：
10.7
通讯作者：
Wright, Stephen I.
中科院分区：
文献类型：
--
作者：
Foxe, John Paul;Dar, Vaqaar-un-Nisa;Wright, Stephen I.
对核苷酸多样性的研究发现，拟南芥中存在过多的低频氨基酸多态性分离，表明在这种近交物种中，弱纯化选择对氨基酸多态性起主导作用。本文研究了拟南芥（Arabidopsis lyrata） 6个远交群体同义和非同义位点的多样性和分化水平，并将这些结果与拟南芥（a.thaliana）进行了比较，以检验基因、群体和物种间突变和选择参数的差异。我们发现，在种群和物种范围内，A. lyrata均表现出过量的低频非同义多态性，这与在A. thaliana中观察到的弱净化选择模式相一致。此外，非同义多态性在羊草种群分布中往往受到限制，这与净化选择阻止其地理传播是一致的。高表达基因在多态性和固定差异上均表现出氨基酸与同义变化的比例降低，表明高表达蛋白具有更强的纯化选择的一般模式。
Studies of nucleotide diversity have found an excess of low-frequency amino acid polymorphisms segregating in Arabidopsis thaliana, suggesting a predominance of weak purifying selection acting on amino acid polymorphism in this inbreeding species. Here, we investigate levels of diversity and divergence at synonymous and nonsynonymous sites in 6 circumpolar populations of the outbreeding Arabidopsis lyrata and compare these results with A. thaliana, to test for differences in mutation and selection parameters across genes, populations, and species. We find that A. lyrata shows an excess of low-frequency nonsynonymous polymorphisms both within populations and species wide, consistent with weak purifying selection similar to the patterns observed in A. thaliana. Furthermore, nonsynonymous polymorphisms tend to be more restricted in their population distribution in A. lyrata, consistent with purifying selection preventing their geographic spread. Highly expressed genes show a reduced ratio of amino acid to synonymous change for both polymorphism and fixed differences, suggesting a general pattern of stronger purifying selection on high-expression proteins.