Table 4.

Number of nucleotide substitutions in conserved vs. variable regions in sequences of Bromius (blind sacs) symbionts and members of the focal clade, and the ratio of the two values (variable/conserved). Numbers given are the mean number of substitutions found in pairwise comparisons. The datasets are explained in section 3.3. The ‘focal clade’ is a group of six sequences containing the symbionts of Donaciinae and a few others (see Figure 2 andFigure 3), in the ‘Enterobacteriaceae’-dataset, the focal clade is more restricted (see Figure 4).

Dataset	Taxa analyzed	Conserved regions	Variable regions	Ratio var./cons.
‘Enterobacteriaceae’	Average within focal clade excl. Bromius	3	78	29.4
	Bromius compared to members of the focal clade	21	116	5.5
‘Bacterial phylogeny’	Average within focal clade	2	154	97.0
	Bromius compared to members of the focal clade	5	147	29.5