Positions of SDR elements in Scenedesmus cpDNA. Lines connect cpDNA loci displaying repeats ≥30 bp with identical sequences either on the same strand or different strands. For this analysis carried out with REPuter, one copy of the IR sequence (IRA) was deleted; the location of this deleted copy is indicated by the long, vertical arrow. The loci containing repeat units A, B and C are represented by symbols of different shapes outside the gene map: triangles, repeat unit A; squares, repeat unit B; circles, repeat unit C. Filled symbols denote the repeats occupying the + strand; open symbols denote the repeats found on the alternate strand. A symbol accompanied by an asterisk indicates the presence of two or more copies. Small arrows point to gene coding regions containing copies of repeat unit B.