Wagner A
The Santa Fe Institute, University of New Mexico, Department of Biology, 167A Castetter Hall, Albuquerque, NM 87131-1091, USA.
Proc Natl Acad Sci U S A. 2000 Jun 6;97(12):6579-84. doi: 10.1073/pnas.110147097.
The neutralist perspective on molecular evolution maintains that the vast majority of mutations affecting gene function are neutral or deleterious. After a gene duplication where both genes are retained, it predicts that original and duplicate genes diverge at clock-like rates. This prediction is usually tested for coding sequences, but can also be applied to another important aspect of gene function, the genes' expression pattern. Moreover, if both sequence and expression pattern diverge at clock-like rates, a correlation between divergence in sequence and divergence in expression patterns is expected. Duplicate gene pairs with more highly diverged sequences should also show more highly diverged expression patterns. This prediction is tested for a large sample of duplicated genes in the yeast Saccharomyces cerevisiae, using both genome sequence and microarray expression data. Only a weak correlation is observed, suggesting that coding sequence and mRNA expression patterns of duplicate gene pairs evolve independently and at vastly different rates. Implications of this finding for the neutralist-selectionist debate are discussed.
分子进化的中性论观点认为，绝大多数影响基因功能的突变是中性或有害的。在基因复制后，如果两个基因都得以保留，该观点预测原始基因和复制基因会以类似时钟的速率发生分化。这一预测通常针对编码序列进行检验，但也可应用于基因功能的另一个重要方面，即基因的表达模式。此外，如果序列和表达模式都以类似时钟的速率发生分化，那么序列分化与表达模式分化之间有望存在相关性。具有更高序列分化程度的复制基因对也应呈现出更高程度的表达模式分化。利用基因组序列和微阵列表达数据，针对酿酒酵母中大量的复制基因样本对这一预测进行了检验。结果仅观察到微弱的相关性，这表明复制基因对的编码序列和mRNA表达模式是独立进化的，且进化速率差异极大。文中讨论了这一发现对中性论者与选择论者争论的影响。
