Figure 2

Evolutionary distribution of ciliary transition zone genes. Stylised eukaryotic tree showing distribution of TZ complex proteins across 6 eukaryotic supergroups. All non-ciliated organisms have been excluded from the table. Plantae are divided into two sub-groups: green algae and mosses/ferns (higher plants are non-ciliate). Both these sub-groups contain ciliated organisms; note that mosses and ferns lack all known TZ complex components. Black circles denote presence of a putative orthologue in >75% ciliated/flagellate organisms analysed in one supergroup. Dark grey, light grey and white circles represent presence in 50-74%, 25-49% and <25% organisms analysed in one supergroup, respectively. The boxed area shows proteins that are present in >50% organisms in every supergroup; these represent the core TZ components. MKS1 is present in >50% of every supergroup but missing from the Rhizaria, which are represented by only a single sequenced organism; additional genome sequences may indicate that MKS1 is also core. Additional file 2 shows a more detailed version listing individual organisms, and the full bioinformatic analysis is available in Additional file 1.