The amount of a genome's sequence that is functional has been surprisingly difficult to estimate accurately. This has severely hindered analyses asking whether the amount of functional genomic sequence correlates with organismal complexity. Most studies estimate these amounts by considering nucleotide substitution rates within aligned sequences. These approaches show reduced power to identify sequence that is aligned, functional, and constrained only within narrowly defined phyla. The neutral indel model exploits insertions or deletions (indels) rather than substitutions in predicting functional sequence. Surprisingly, this method indicates that half of all functional sequence is specific to individual eutherian lineages. This review considers the rates at which coding or noncoding and functional or nonfunctional sequence changes among mammalian genomes. In contrast to the slow rate at which protein-coding sequence changes, functional noncoding sequence appears to change or be turned over at rapid rates in mammals.

中文翻译：

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人类和其他基因组中功能序列的快速更新。

有功能的基因组序列的数量令人惊讶地难以准确估计。这严重阻碍了分析功能基因组序列的数量是否与有机体复杂性相关。大多数研究通过考虑比对序列中的核苷酸取代率来估计这些数量。这些方法显示出识别仅在狭窄定义的门内对齐、功能和约束的序列的能力降低。中性插入缺失模型利用插入或缺失（插入缺失）而不是替换来预测功能序列。令人惊讶的是，这种方法表明所有功能序列的一半是特定于个别 eutherian 谱系的。这篇综述考虑了哺乳动物基因组中编码或非编码以及功能或非功能序列变化的速率。与蛋白质编码序列变化的缓慢速率相反，功能性非编码序列似乎在哺乳动物中快速变化或翻转。