The evolutionary demography of duplicate genes.
The evolutionary demography of duplicate genes.
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DOI：
10.1023/a:1022696612931
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发表时间：
2003-01-01
期刊：
影响因子：
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通讯作者：
Conery, John S.
中科院分区：
文献类型：
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作者：
Lynch, Michael;Conery, John S.
尽管基因复制通常被视为进化新颖性起源的必要材料来源，但基因复制的起源、丢失和保存率尚不清楚。将稳态人口统计技术应用于七个完全测序的基因组中普查的重复基因的年龄分布，我们估计真核基因的平均重复率约为 0.01/基因/百万年，这与每个核苷酸位点的突变率处于同一数量级。然而，重复基因的平均半衰期相对较短，约为 400 万年。这些比率的显着种间差异似乎是由于准平衡出生-死亡过程而出现的物种特异性基因组大小差异的原因。大多数复制基因在其历史早期经历了短暂的宽松选择期，少数表现出定向选择的特征，但那些存活超过几百万年的基因最终经历了强烈的纯化选择。因此，尽管大多数关于基因复制过程的理论工作都集中在与适应性进化相关的问题上，但新功能的起源对于复制基因来说似乎是非常罕见的命运。复制过程的一个更重要的作用可能是通过替代拷贝的相互沉默产生微染色体重排，这可能导致早期物种的后代谱系中合子后生殖障碍的被动起源。
Although gene duplication has generally been viewed as a necessary source of material for the origin of evolutionary novelties, the rates of origin, loss, and preservation of gene duplicates are not well understood. Applying steady-state demographic techniques to the age distributions of duplicate genes censused in seven completely sequenced genomes, we estimate the average rate of duplication of a eukaryotic gene to be on the order of 0.01/gene/million years, which is of the same order of magnitude as the mutation rate per nucleotide site. However, the average half-life of duplicate genes is relatively small, on the order of 4.0 million years. Significant interspecific variation in these rates appears to be responsible for differences in species-specific genome sizes that arise as a consequence of a quasi-equilibrium birth-death process. Most duplicated genes experience a brief period of relaxed selection early in their history and a minority exhibit the signature of directional selection, but those that survive more than a few million years eventually experience strong purifying selection. Thus, although most theoretical work on the gene-duplication process has focused on issues related to adaptive evolution, the origin of a new function appears to be a very rare fate for a duplicate gene. A more significant role of the duplication process may be the generation of microchromosomal rearrangements through reciprocal silencing of alternative copies, which can lead to the passive origin of post-zygotic reproductive barriers in descendant lineages of incipient species.