Air carries a vast number of bacteria and viruses over great distances all the time. This leads to continuous introduction of foreign genetic material to local, established microbial communities. In this perspective, I ask whether this silent rain may have a slowing effect on the overall evolutionary rates in the microbial biosphere. Arguably, the greater the genetic divergence between gene ‘donors’ and ‘recipients’, the greater the chance that the gene product has a deleterious epistatic interaction with other gene products in its genetic environment. This is due to the long-term absence of check for mutual compatibility. As such, if an organism is extensively different from other bacteria, genetic innovations are less probable to fit to the genome. Here, genetic innovation would be anything that elevates the fitness of the gene vehicle (e.g. bacterium) over its contemporaries. Adopted innovations increase the fitness of the compatible genome over incompatible ones, thus possibly tempering the pace at which mutations accumulate in existing genomes over generations. I further discuss the transfer of bacteriophages through atmosphere and potential effects that this may have on local dynamics and perhaps phage survival.

中文翻译：

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无声雨：微生物介导的大气介导的连通性是否影响细菌的进化速率？

空气一直在很远的距离携带大量细菌和病毒。这导致将外国遗传物质不断引入当地已建立的微生物群落。从这个角度来看，我想问这种静寂的雨水是否会对微生物生物圈的整体进化速率产生减慢的影响。可以说，基因“供体”和“接受者”之间的遗传差异越大，基因产物在其遗传环境中与其他基因产物发生有害的上位相互作用的机会就越大。这是由于长期缺乏相互兼容性检查。这样，如果一种生物与其他细菌有很大不同，那么遗传创新就不太可能适合基因组。在这里，基因创新可以提高基因载体的适用性（例如 细菌）。与不兼容的基因组相比，采用的创新技术提高了兼容基因组的适应性，因此有可能缓和了几代人在现有基因组中积累突变的速度。我将进一步讨论噬菌体通过大气的转移及其对局部动力学和噬菌体存活的潜在影响。