蚜虫与其初级内共生菌进化关系：假说及演化机理

Evolutionary relationships between aphids and their primary endosymbionts: hypotheses and evolution mechanisms

蚜虫是半翅目(Hemiptera)中一类取食植物韧皮部汁液的昆虫,由于具有一些独特的生物学特征,是研究重要适应进化问题的理想模型。蚜虫体内存在一类专性的胞内共生菌Buchnera,对于蚜虫营养代谢和正常发育有重要贡献,被称为蚜虫的初级内共生菌。蚜虫-Buchnera是研究共生关系的理想模型,两者系统发育格局的研究有助于理解生物间专性共生关系的演化。本文系统综述了两者在不同分类水平(高级阶元、低级阶元)上的系统发育关系研究。现有证据暗示:两者在低级阶元水平上具有系统发育一致性,而在高级阶元水平上可能没有平行演化关系,这些对早期研究提出的平行演化假说提出了质疑。在现有研究的基础上,本文建议从增加取样类群、增加基因数目和数据量、系统发育一致性检验等几个方面开展更深入的系统发育研究,并开展Buchnera的转移实验,从而检验Buchnera的横向转移及其基因在不同蚜虫支系中的进化速率一致性,以便更客观地揭示蚜虫-Buchnera的进化关系。

Aphids are a group of phloem-feeding hemipteran insects.Due to their some unique biological features,aphids are good model organisms for understanding many significant theoretical issues in adaptive evolution.Aphids maintain an obligate endosymbiotic association with Buchnera,their primary endosymbionts,which are nutritionally and developmentally indispensable to aphids.Studies on phylogenetic relationships between aphids and Buchnera help us understand the evolution of obligate symbiosis.In this article we reviewed the advances in phylogenetic relationships between aphids and Buchnera at different taxonomic levels（from higher to lower）.Available evidences indicate that parallel diversifications of aphids and Buchnera occur at lower taxonomic level.However,such relationships may not exist at higher taxonomic level,which contradicts with the traditionally accepted parallelism hypothesis.On the basis of the detailed review of previous studies,it is proposed that more taxonomic groups should be sampled and more genomic data as well as robust phylogenetic concordance tests should be used.Furthermore,Buchnera horizontal transfer and consistency of evolutionary rates of Buchnera genes among different aphid lineages should be investigated to clarify the evolutionary relationships between aphids and Buchnera.