Biological species are universal across Life's domains.
Biological species are universal across Life's domains.
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生物物种在生命领域是普遍存在的。
DOI：
10.1093/gbe/evx026
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发表时间：
2017-02-10
影响因子：
3.3
通讯作者：
Ochman H
中科院分区：
文献类型：
--
作者：
Bobay LM;Ochman H
物种的划分是组织和理解生物多样性的基础。最广泛应用的区分物种的标准是生物物种概念(BSC)，它将物种定义为与其他此类群体保持生殖隔离的杂交个体的群体。BSC具有广泛的吸引力；然而，许多生物，最明显的无性血统，不能根据BSC进行分类。尽管细菌和古生菌只有无性繁殖模式，但它们可以通过同源重组转移和交换基因。在这里，我们展示了同源基因交换的障碍定义了原核生物中的生物物种，具有与有性真核生物相同的效力。通过分析重组对数千个基因组序列中多态性的影响，我们发现超过一半的命名细菌物种在测序成分之间进行了连续重组，表明了真实的生物物种。然而，近四分之一的已命名细菌物种表现出明显的不连续性，并包括多种生物物种。这些基因流动的中断并不是基因组同一性的简单函数，表明细菌物种形成并不是通过基因组序列的逐渐分化而统一进行的。基于重组多态的相同基因组方法检索有性繁殖真核生物中已知的物种边界。因此，基于基因流的单一生物物种定义，一度被认为仅限于有性繁殖的生物体，适用于所有细胞生命形式。
Delineation of species is fundamental to organizing and understanding biological diversity. The most widely applied criterion for distinguishing species is the Biological Species Concept (BSC), which defines species as groups of interbreeding individuals that remain reproductively isolated from other such groups. The BSC has broad appeal; however, many organisms, most notably asexual lineages, cannot be classified according to the BSC. Despite their exclusively asexual mode of reproduction, Bacteria and Archaea can transfer and exchange genes though homologous recombination. Here we show that barriers to homologous gene exchange define biological species in prokaryotes with the same efficacy as in sexual eukaryotes. By analyzing the impact of recombination on the polymorphisms in thousands of genome sequences, we find that over half of named bacterial species undergo continuous recombination among sequenced constituents, indicative of true biological species. However, nearly a quarter of named bacterial species show sharp discontinuities and comprise multiple biological species. These interruptions of gene flow are not a simple function of genome identity, indicating that bacterial speciation does not uniformly proceed by the gradual divergence of genome sequences. The same genomic approach based on recombinant polymorphisms retrieves known species boundaries in sexually reproducing eukaryotes. Thus, a single biological species definition based on gene flow, once thought to be limited only to sexually reproducing organisms, is applicable to all cellular lifeforms.