Robustness of nodes was assessed with 100 NJ- resp. ML-bootstrap replicates.
However, as PAUP does not allow for site-specific rates in bootstrap analysis, ML bootstrapping for trmD and gyrB was performed with gamma distributed rates, with 100 bootstrap replicates. Bootstrap values were then plotted on the phylogeny obtained with the original model with site-specific rates. Bayesian analyses were performed as implemented in MrBayes 3.1.2 . Models used were GTR + G (wsp), GTR + I (ftsZ), GTR (groEL, 16S rDNA), and GTR with separate rates for each codon position (trmD, gyrB). For the concatenated dataset, the same models were used for each gene partition. Analyses were initiated from random starting trees. Two separate Markov Chain Monte Carlo (MCMC) runs, each composed of four chains (one cold and selleck chemicals llc three heated), were run for 6,000,000 generations (7,000,000 generations
for the Selleck CB-839 concatenated Wolbachia set). The cold chain was sampled every 100 generations, the first 15,000 generations were discarded afterwards (burn-in of 25%). Posterior probabilities were computed from the remaining trees. We checked whether the MCMC analyses ran long enough using the program AWTY . Stationarity was assumed when there was convergence between the two MCMC runs and when the cumulative posterior probabilities of splits stabilized; in all analyses 6,000,000 generations proved sufficient. The concatenated Wolbachia dataset however, showed no convergence or stabilization of probabilities (not even after 15,000,000 generations). This is most likely due to the extensive recombination present within this dataset. Analysis of recombination Evidence for recombination within Wolbachia and Cardinium was obtained by comparing topologies of different genes. For Wolbachia, we also quantified the relative impact of recombination compared to point mutation over short-term clonal diversification. Following standard MLST protocol , we assigned selleck chemicals allele identifiers
for each unique sequence at a particular locus, and an “ST” (sequence type) for each unique allelic profile. We used eBURST version 3  (Figure 2) to identify closely related pairs or clusters (clonal complexes). All members assigned to a clonal complex share identical alleles at three of the four loci with at least one other ST member of the complex. By comparing, for each ST within a clonal complex, N-acetylglucosamine-1-phosphate transferase the sequence of the deviating allele with the allele of the founding genotype, it is possible to estimate how many STs have arisen by de novo point mutation (i.e. a novel change at a single base) or homologous recombination (a single non-unique change or multiple nucleotide changes) . Additionally, single gene alignments for Wolbachia and Cardinium were checked for signs of intragenic recombination using the software package RDP3  and by visual inspection. Programs used in the RDP3 software package were RDP, Geneconv, Bootscan, MaxChi, Chimaera, and Sister Scanning.