Fine-scale cospeciation between Brachycaudus and Buchnera aphidicola: bacterial genome helps define species and evolutionary relationships in aphids
Fine-scale cospeciation between Brachycaudus and Buchnera aphidicola: bacterial genome helps define species and evolutionary relationships in aphids
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DOI：
10.1098/rspb.2008.0679
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发表时间：
2009-01-07
影响因子：
4.7
通讯作者：
Coeur d'Acier, Armelle
中科院分区：
文献类型：
--
作者：
Jousselin, Emmanuelle;Desdevises, Yves;Coeur d'Acier, Armelle
蚜虫体内有一种必需的共生体--棉铃虫(Buchnera Aphidicola)，它提供的必需氨基酸不是它们的食物所提供的。这些细菌是垂直传播的，系统发育分析表明它们与宿主是“同种”的。我们在很好的分类水平上研究了这种同种现象，在短尾棉蚜属内。我们在这两种生物中使用了基于DNA的物种划分方法，以避免在定义蚜虫和Buchnera物种时存在偏见，并在不假定特定相互作用的情况下推断关联模式。我们的研究结果对短尾轮虫的某些‘分类’种提出了质疑，并表明，长尾短尾短尾轮虫已经分化为独立进化的实体，每个实体特定于一个‘系统发育’短尾轮虫物种。我们还发现，布赫内拉和它们的宿主同时进行了多样化，并行。这些结果验证了使用Buchnera DNA数据来推断其宿主的进化史。Buchnera基因组进化迅速，使其成为解决蚜虫分类中歧义问题的完美工具。这项研究还强调了物种定界方法在涉及难以概念化的物种的共种研究中的作用--细菌就是这种情况--以及在相互作用的生物体的分类尚未独立确定且物种定义取决于寄主联系的情况下。
Aphids harbour an obligatory symbiont, Buchnera aphidicola, providing essential amino acids not supplied by their diet. These bacteria are transmitted vertically and phylogenic analyses suggest that they have 'cospeciated' with their hosts. We investigated this cospeciation phenomenon at a fine taxonomic level, within the aphid genus Brachycaudus. We used DNA-based methods of species delimitation in both organisms, to avoid biases in the definition of aphid and Buchnera species and to infer association patterns without the presumption of a specific interaction. Our results call into question certain 'taxonomic' species of Brachycaudus and suggest that B. aphidicola has diversified into independently evolving entities, each specific to a 'phylogenetic' Brachycaudus species. We also found that Buchnera and their hosts simultaneously diversified, in parallel. These results validate the use of Buchnera DNA data for inferring the evolutionary history of their host. The Buchnera genome evolves rapidly, making it the perfect tool for resolving ambiguities in aphid taxonomy. This study also highlights the usefulness of species delimitation methods in cospeciation studies involving species difficult to conceptualize-as is the case for bacteria-and in cases in which the taxonomy of the interacting organisms has not been determined independently and species definition depends on host association.