Figure 4

Maximum likelihood (ML) Wolbachia phylogenetic tree based on the addition to the alignment reported in Zhou et al (1998) of wsp gene sequence data from five male-killing Wolbachia strains, the strain infecting C. scorpioides, and two strains from each of the Wolbachia groups C, D and G. Wolbachia strains are identified by their host taxon name and GenBank accession number (in parentheses). Wolbachia groups are indicated (A–D and G). For the ML analysis, we used a GTR+G+I substitution model (number of substitution types=6; nucleotide frequencies: A=0.320; C=0.153; G=0.210; T=0.317; proportion invariable sites=0.326 and gamma shape parameter (alpha)=1.893) selected by MODELTEST v3.6 (Posada and Crandall, 1998), and implemented in PAUP^* (Swofford, 2002). Values above branches denote percent support for clades based on 100 bootstrap replicates. Wolbachia strains implicated in male killing are indicated by double asterisks.