Spaulding A W, von Dohlen C D
Department of Biology, Utah State University, Logan, UT 84322 USA.
Insect Mol Biol. 2001 Feb;10(1):57-67. doi: 10.1046/j.1365-2583.2001.00231.x.
Eubacterial 16S rDNAs were sequenced from endosymbionts of seven psyllids (Psylloidea) and one whitefly (Aleyrodoidea), to investigate the evolution of endosymbionts and their hosts. Primary endosymbionts from all psyllids formed a highly supported clade, tentatively placed as the sister to whitefly primary endosymbionts, and showing several points of congruence with the host morphological phylogeny. Almost all host taxa yielded an additional eubacterial sequence, related either to known psyllid secondary endosymbionts or to other insect endosymbionts or parasites. The relationships of some secondary endosymbionts also suggested cospeciation with psyllid hosts, or ancient horizontal transfers. All primary endosymbionts, and some secondary endosymbionts, exhibited molecular genetic effects of a long-term, intracellular existence in their biased nucleotide content and decreased stability of rRNA secondary structure.
对7种木虱（木虱总科）和1种粉虱（粉虱总科）的内共生菌的真细菌16S rDNA进行了测序，以研究内共生菌及其宿主的进化。所有木虱的初级内共生菌形成了一个得到高度支持的分支，暂时被定位为粉虱初级内共生菌的姐妹分支，并且在几个方面与宿主形态系统发育一致。几乎所有宿主类群都产生了另一种真细菌序列，该序列与已知的木虱次级内共生菌、其他昆虫内共生菌或寄生虫有关。一些次级内共生菌之间的关系也表明它们与木虱宿主共同物种形成，或发生了古老的水平转移。所有初级内共生菌以及一些次级内共生菌，在其偏向的核苷酸含量和rRNA二级结构稳定性降低方面，都表现出长期细胞内生存的分子遗传效应。
