Expression patterns of Sep2 and Sep5. Expression of Sep2 and Sep5 was detected in Drosophila species by in situ hybridization as shown in the top and bottom panels, respectively. Purple coloration indicates presence of mRNA. Cladograms show the relationships of the species investigated. Numbers on individual panels indicate the number of embryos assessed with consistent staining patterns. Sep5 showed domains of more intense staining during cellular blastoderm stages in D. melanogaster and D. willistoni; these domains are indicated by black bars. Stage ranges are according to [24]: 0–2, syncytial blastoderm; 3-4, cellular blastoderm; 9-10, during germ-band elongation; 14–16, final embryonic stages. Staining during stages 0–2 indicates presence of maternal transcripts [25]. Dmel, D. melanogaster; Dyak, D. yakuba; Dpse, D. pseudoobscura; Dwil, D. willistoni; Dmoj, D. mojavensis; Dvir, D. virilis.