Figure 1

Mollicute phylogenetic tree including species for which at least one genome sequence is available. The mollicute evolutionary history was inferred by using the Maximum Likelihood method based on the Tamura-Nei model [9]. The tree with the highest log likelihood (−8994.2924) is shown. The percentage of trees in which the associated taxa clustered together is shown next to the branches. Initial tree(s) for the heuristic search were obtained automatically as follows. When the number of common sites was < 100 or less than one fourth of the total number of sites, the maximum parsimony method was used; otherwise BIONJ method with MCL distance matrix was used. A discrete Gamma distribution was used to model evolutionary rate differences among sites (5 categories (+G, parameter = 0.5355)). The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. Nucleotide sequences (16S rDNA) from 30 species were aligned. After removing all positions containing gaps and missing data, the final dataset included 1136 positions.Evolutionary analyses were conducted in MEGA5 [10]. The number in parentheses indicates the number of plasmids previously described for each species. No indication means that there is no reported evidence of plasmid in these species. For M. mycoides subsp. capri, each one of the three plasmids was identified in a different strain. The letters on the right side of the figure indicate the phylogenetic groups within the Mollicutes: S, Spiroplasma; H: Hominis; P: Pneumoniae; AP: Acholeplasma-Phytoplasma; M: Mycoplasma mycoides cluster.