Maintaining sexual reproduction in a highly competitive world is still one of the major mysteries of biology given the apparently high efficiency of asexual reproduction. Co‐evolutionary theories such as the Red Queen hypothesis would suggest that the microbiomes in human reproductive systems, specifically the microbiomes contained in semen and vaginal fluids, should reach some level of homogeneity thanks to arguably the most conspicuous microbiome transmission between two sexes. The long‐term sexual coevolution should favor the dynamic homogeneity or stability, which should also be beneficial for sexual reproduction such as sperm survival or fertilization on physiological/ecological time scale. We present a piece of quantitative evidence in the form of microbial community spatial heterogeneity to support the stability notion by analyzing three big datasets of the human vaginal, semen and gut microbiome. Methodologically, we applied a recent community‐level extension to the classic Taylor's power law, which reached the rare status of ecological law and has found applications beyond biology. Both ecological and evolutionary theories, such as hologenome/holobiont and Red Queen, as well as consideration of first principles, would predict that microbiome transmissions between two sexes should have homogenizing effects on the composition and stability of the microbiomes in human reproductive systems, and therefore have similar variance structures. This is supported by the finding that the power law analysis revealed human vaginal and semen microbiomes exhibited the same scaling parameter size in their community spatial (inter‐individual) heterogeneities, while the both exhibited significantly different heterogeneity scaling parameter size with the human gut microbiome.

中文翻译：

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人类生殖系统微生物组表现出与肠道微生物组显着不同的异质性标度，但系统内标度不变

考虑到无性生殖的效率很高，在竞争激烈的世界中维持有性生殖仍然是生物学的主要谜团之一。诸如Red Queen假说之类的共同进化理论表明，人类生殖系统中的微生物群，特别是精液和阴道液中的微生物群，应该达到一定程度的同质性，这归功于两个性别之间最明显的微生物群传播。长期的性进化应有利于动态同质性或稳定性，这也应有利于性繁殖，例如在生理/生态学时标上的精子存活或受精。我们通过分析人类阴道，精液和肠道微生物组的三个大数据集，以微生物群落空间异质性的形式提供了定量证据，以支持稳定性概念。在方法论上，我们对经典的泰勒幂定律应用了最新的社区级扩展，从而达到了生态法的罕见地位，并发现了生物学以外的应用。生态学和进化论，例如全基因组/全生命周期论和红女王，以及对第一性原理的考虑，都预示着两性之间的微生物组传播应对人类生殖系统中微生物组的组成和稳定性产生均质作用，因此具有相似的方差结构。