Sequence logos summarizing repeat sequence variation in Fungi, Ecdysozoa, and Deuterostomia. Sequence logos were generated from all heptad repeat sequences of relevant species using the LogOddsLogo tool . Most repeat positions are strongly conserved, but different clades exhibit different variations. Lysine is particularly common at position seven in Deuterostomia. See Additional file 1 for RPB1 sequences for all species examined.