Ambur Ole Herman, Engelstädter Jan, Johnsen Pål J, Miller Eric L, Rozen Daniel E
Department of Life Sciences and Health, Oslo and Akershus University College of Applied Sciences, 1478 Oslo, Norway.
School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia.
Philos Trans R Soc Lond B Biol Sci. 2016 Oct 19;371(1706). doi: 10.1098/rstb.2015.0528.
Many bacteria are highly sexual, but the reasons for their promiscuity remain obscure. Did bacterial sex evolve to maximize diversity and facilitate adaptation in a changing world, or does it instead help to retain the bacterial functions that work right now? In other words, is bacterial sex innovative or conservative? Our aim in this review is to integrate experimental, bioinformatic and theoretical studies to critically evaluate these alternatives, with a main focus on natural genetic transformation, the bacterial equivalent of eukaryotic sexual reproduction. First, we provide a general overview of several hypotheses that have been put forward to explain the evolution of transformation. Next, we synthesize a large body of evidence highlighting the numerous passive and active barriers to transformation that have evolved to protect bacteria from foreign DNA, thereby increasing the likelihood that transformation takes place among clonemates. Our critical review of the existing literature provides support for the view that bacterial transformation is maintained as a means of genomic conservation that provides direct benefits to both individual bacterial cells and to transformable bacterial populations. We examine the generality of this view across bacteria and contrast this explanation with the different evolutionary roles proposed to maintain sex in eukaryotes. This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
许多细菌具有高度的“性”特征，但它们这种滥交行为的原因仍不明确。细菌的“性”是为了在不断变化的世界中最大化多样性并促进适应性进化，还是仅仅有助于保留当前正常运作的细菌功能？换句话说，细菌的“性”是创新的还是保守的？在这篇综述中，我们的目的是整合实验、生物信息学和理论研究，以批判性地评估这些观点，主要聚焦于自然遗传转化，即细菌中与真核生物有性生殖相对应的过程。首先，我们概述了几种为解释转化进化而提出的假说。接下来，我们综合大量证据，强调了为保护细菌免受外源DNA影响而进化出的众多转化的被动和主动障碍，从而增加了克隆菌之间发生转化的可能性。我们对现有文献的批判性综述支持了这样一种观点，即细菌转化作为一种基因组保守的方式得以维持，这对单个细菌细胞和可转化细菌群体都有直接益处。我们研究了这一观点在细菌中的普遍性，并将这种解释与为维持真核生物有性生殖而提出的不同进化作用进行对比。本文是主题为“怪异的性：未被充分认识的有性生殖多样性”特刊的一部分。
