毛蚜属Chaitophorus蚜虫(半翅目:蚜科:毛蚜亚科)与初级内共生菌Buchnera的演化关系

Study of the evolutionary relationship between Chaitophorus aphids and their primary endosymbiont Buchnera(Hemiptera:Aphididae:Chaitophorinae)

【目的】蚜虫体内共生菌种类丰富,二者关系十分密切。几乎所有蚜虫都具有一类专性的初级内共生菌Buchnera aphidicola,二者的专性共生关系使蚜虫-Buchnera成为研究共生关系演化的理想模型。本研究对蚜虫-Buchnera在低级阶元水平上的"平行演化假说"进行了验证。【方法】选取在杨属Populus或柳属Salix植物上营同寄主全周期生活的毛蚜属Chaitophorus蚜虫作为研究对象,基于不同来源的分子标记(蚜虫线粒体基因、核基因和内共生菌基因),运用最大似然法和贝叶斯法重建蚜虫和Buchnera的系统树,并利用Tree Map、Jane和Para Fit检验二者是否具有协同系统发生关系。【结果】Tree Map和Jane分析检测到毛蚜属蚜虫与Buchnera具有显著的共成种信号,Para Fit分析结果表明二者的总体关联极为显著。【结论】毛蚜属蚜虫与其初级内共生菌Buchnera在种级及以下水平上符合"平行演化假说",并且二者的演化关系不会受到寄主植物差异的影响。

[Objectives] Aphids harbor various symbionts, all of which have a close endosymbiotic relationship with their hosts. For example, almost all aphids harbor an obligatory primary endosymbiont, Buchnera aphidicola. Due to this almost universal, obligate, endosymbiotic relationship, Buchnera is an ideal model for studying the evolution of mutualism. This study tested the parallelism hypothesis between aphids and Buchnera. [Methods] Species from the aphid genus Chaitophorus, which are monocious and holocyclic on Populus and Salix, were chosen for study. We reconstructed the phylogenies of Chaitophorus and Buchnera based on different kinds of molecular markers （i.e., mitochondrial and nuclear genes of aphids and genes derived from Buchnera）, using both maximum likelihood and Bayesian methods. The phylogenetic congruence between aphids and Buchnera was tested with TreeMap, Jane and ParaFit. [Results] TreeMap and Jane analyses confirmed a significant pattern of cophylogeny between Chaitophorus and Buchnera. ParaFit analyses indicated that their overall correlation was extremely significant. [Conclusion] Our results provide strong evidence for the parallel evolution of Chaitophorus and Buchnera at the intraspecific, and interspecific, and taxonomic levels. In addition, the evolutionary relationships between Chaitophorus and Buchnera are not affected by host plants.