Gene conversion between mitochondrial and chloroplast small subunit rRNA genes. (A) The spatial distribution of substitutions (vertical lines) in mitochondrial rrn18 that distinguish Silene latifolia from Beta vulgaris (regions that could not be reliably aligned in a multiple species alignment were excluded). The black box indicates the region shown in detail below. (B) Aligned sequences of angiosperm mitochondrial rrn18 and chloroplast rrn16. Dots in the alignment indicate sequence identity with the Zea reference sequence. The red box shows the minimal extent of the region inferred to have experienced a gene conversion event, which also corresponds to the position of helix 240 in E. coli 16S rRNA . Analysis of these sequences with GENECONV v1.81a using a mismatch cost of 1 found highly significant evidence for gene conversion in this region (p < 0.0001). The asterisk indicates the inferred phylogenetic timing of that event. Gene sequences were taken from published genomes (see Figure 1) with the exception S. acaulis and S. vulgaris rrn18 (GenBank EF547249 and HM562728) and S. latifolia rrn16 (AB189069).