Sexual isolation and speciation in bacteria
Sexual isolation and speciation in bacteria
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DOI：
10.1023/a:1021232409545
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发表时间：
2002-11-01
期刊：
影响因子：
1.5
通讯作者：
Cohan, FM
中科院分区：
文献类型：
--
作者：
Cohan, FM
像所有其他生物一样，细菌能够进行有性重组。然而，与大多数植物和动物不同，细菌很少重组，而且当它们重组时，它们在选择性伴侣时非常混乱。在细菌世界中，通过重组可以跨越的进化距离可能没有绝对的限制，但种间重组会因各种因素而减少，包括生态隔离，行为隔离，DNA进入障碍，限制性内切酶活性，对不同DNA序列整合的抗性，错配修复逆转重组，以及重组片段的功能不相容性。通常，单个细菌物种对于大多数这些因素是遗传可变的。因此，自然选择可以调节性隔离的水平，以增加对受体有用的基因的转移，同时最大限度地减少有害基因的转移。当重组涉及足够长以转移适应的短片段时，种间重组被优化，而不共转移适应侧翼的潜在有害DNA。自然选择显然起到了减少细菌物种之间的性隔离的作用。性隔离的进化并不是细菌物种形成的里程碑，因为细菌重组太罕见，无法对抗早期物种之间的适应性分化。具有讽刺意味的是，早期细菌物种之间的重组实际上可能会促进物种形成过程，阻止一个早期物种在竞争中超过另一个物种而灭绝。种间重组也可以通过引入来自不同物种的新基因位点来促进物种形成，从而允许新生态位的入侵。
Like organisms from all other walks of life, bacteria are capable of sexual recombination. However, unlike most plants and animals, bacteria recombine only rarely, and when they do they are extremely promiscuous in their choice of sexual partners. There may be no absolute constraints on the evolutionary distances that can be traversed through recombination in the bacterial world, but interspecies recombination is reduced by a variety of factors, including ecological isolation, behavioral isolation, obstacles to DNA entry, restriction endonuclease activity, resistance to integration of divergent DNA sequences, reversal of recombination by mismatch repair, and functional incompatibility of recombined segments. Typically, individual bacterial species are genetically variable for most of these factors. Therefore, natural selection can modulate levels of sexual isolation, to increase the transfer of genes useful to the recipient while minimizing the transfer of harmful genes. Interspecies recombination is optimized when recombination involves short segments that are just long enough to transfer an adaptation, without co-transferring potentially harmful DNA flanking the adaptation. Natural selection has apparently acted to reduce sexual isolation between bacterial species. Evolution of sexual isolation is not a milestone toward speciation in bacteria, since bacterial recombination is too rare to oppose adaptive divergence between incipient species. Ironically, recombination between incipient bacterial species may actually foster the speciation process, by prohibiting one incipient species from out-competing the other to extinction. Interspecific recombination may also foster speciation by introducing novel gene loci from divergent species, allowing invasion of new niches.