Fig. 2.—

Mitochondrial gene arrangements of Octocorallia. (a) The four previously known octocoral genome arrangements. Blocks of genes that are conserved among species are color-coded: pink: block 1, cox1–rns–nad1–cob; blue: block 2, nad6–nad3–nad4l; yellow: block 3, mtMutS–rnl–nad2–nad5–nad4; green: block 4, trnM–cox3–atp6–atp8–cox2. Gene order A (Briareum asbestinum) is presumed to be ancestral. Arrows and dotted lines show inversions of blocks necessary to generate gene orders B (Keratoisidinae), C (Paracorallium japonicum), and D (Corallium konojoi) from A. a, b, locations of inverted repeats in genomes C, D. Heavy line below gene names indicates genes encoded on light strand. (b) Gene order E (Paraminabea aldersladei) hypothesized to have arisen from ancestral gene order A by long-range inversion of block 2.