Figure 1

16S rRNA phylogeny of Columbicola spp. symbionts. Phylogeny of Columbicola spp. symbionts (bold) and related bacteria based on maximum likelihood and Bayesian analyses of a 1.46-kbp fragment of 16S rRNA gene sequences. Insect symbionts are designed by the prefix “PE” (primary endosymbiont), “SE” (secondary endosymbiont) or “E” (if unknown), followed by insect host name and common name (or latin name of bird host for Columbicola spp.) The numbers adjacent to nodes indicate maximum likelihood bootstrap values (to left of diagonal line) and Bayesian posterior probabilities, where applicable (to right of line), for nodes with bootstrap support >50% and Bayesian posterior probabilities >0.5. Asterisks indicate nodes with 100% bootstrap support and Bayesian posterior probability = 1. The bold arrow highlights the location of the sequence derived from strain HS, the recently characterized progenitor of the Sodalis-allied symbionts. Numbers in parentheses represent the G + C content of the 16S rRNA sequences. Final numbers correspond to sample numbers in Additional file 5.