Genome sequencing has revealed that prophages, viral sequences integrated in a bacterial chromosome, are abundant, accounting for as much as 20% of the bacterial genome. These sequences can confer fitness benefits to the bacterial host, but may also instigate cell death through induction. Several recent investigations have revealed that the distribution of prophage lengths is bimodal, with a clear distinction between small and large prophages. Here we develop a mathematical model of the evolutionary forces affecting the prophage size distribution, and fit this model to three recent data sets. This approach offers quantitative estimates for the relative rates of lysogeny, induction, mutational degradation and selection acting on a wide class of prophage sequences. The model predicts that large prophages are predominantly maintained by the introduction of new prophage sequences through lysogeny, whereas shorter prophages can be enriched when they no longer encode the genes necessary for induction, but still offer selective benefits to their hosts.

中文翻译：

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量化维持细菌基因组中噬菌体的力。

基因组测序表明，噬菌体是整合在细菌染色体中的病毒序列，数量丰富，占细菌基因组的20％。这些序列可以赋予细菌宿主健康的益处，但是也可以通过诱导来诱导细胞死亡。最近的一些调查表明，噬菌体长度的分布是双峰的，在大小噬菌体之间有明显的区别。在这里，我们建立了影响预言规模分布的进化力的数学模型，并将该模型拟合到三个最新数据集。这种方法提供了定量估计，涉及相对广泛的噬菌体序列的溶源性，诱导，突变降解和选择的相对速率。