The evolution of bacterial endosymbiont genomes is strongly influenced by host-driven selection. Factors affecting host genome evolution will potentially affect endosymbiont genomes in similar ways. One potential outcome is correlations in molecular rates between the genomes of the symbiotic partners. Recently, we presented the first evidence of such correlations between the mitochondrial genomes of cockroaches and the genomes of their endosymbiont (Blattabacterium cuenoti). Here we investigate whether similar patterns are found in additional host-symbiont partners. We use partial genome data from multiple strains of the bacterial endosymbionts Buchnera aphidicola and Sulcia muelleri, and the mitochondrial genomes of their sap-feeding insect hosts. Both endosymbionts show phylogenetic congruence with the mitochondria of their hosts, a result that is expected due to their identical mode of inheritance. We compared root-to-tip distances and branch lengths of phylogenetically independent species pairs. Both analyses showed a highly significant correlation of molecular rates between the genomes of Buchnera and the mitochondrial genomes of their hosts. A similar correlation was detected between Sulcia and their hosts, but was not statistically significant. Our results indicate that evolutionary rate correlations between hosts and long-term symbionts may be a widespread phenomenon.

细菌内共生体基因组的进化受到宿主驱动选择的强烈影响。影响宿主基因组进化的因素可能会以类似的方式影响内共生体基因组。一种潜在的结果是共生伙伴基因组之间分子率的相关性。最近，我们首次提供了蟑螂线粒体基因组与其内共生菌（Blattabacterium cuenoti）基因组之间这种相关性的第一个证据。在这里，我们调查是否在其他宿主共生伙伴中发现了类似的模式。我们使用来自细菌内共生菌Buchnera aphidicola和Sulcia muelleri 的多个菌株的部分基因组数据，以及它们以树液为食的昆虫宿主的线粒体基因组。两种内共生体都显示出与其宿主线粒体的系统发育一致性，这是由于它们的遗传模式相同而预期的结果。我们比较了系统发育独立物种对的根尖距离和分支长度。两种分析都表明Buchnera基因组与其宿主线粒体基因组之间的分子率具有高度显着的相关性。在Sulcia与其宿主之间检测到类似的相关性，但没有统计学意义。我们的结果表明宿主和长期共生体之间的进化速率相关性可能是一种普遍现象。