在亚群体间缺乏基因流动时，群体间的遗传差异开始累积。
In the absence of gene flow between the subpopulations, genetic differences between the groups begin to accumulate.
它还控制基因保护细胞不受高活性氧自由基这种被认为通过其在DNA上造成的累积损害导致人衰老的分子的侵害。
It also controls genes that protect cells from highly reactive oxygen radicals - molecules often thought to drive human ageing through the cumulative damage they wreak on DNA.
原因在于，当一个理想版本基因“扫描”一个人群，变异便开始在DNA中逐渐累积，这会将基因的统一性——基因扫描的证据——加以破坏。
The reason is that after a favored version of a gene has swept through the population, mutations start building up in its DNA, eroding the uniformity that is evidence of a sweep.
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