Figure 1
Gap and maternal co-ordinate genes in different dipteran species. This figure shows a simplified phylogeny of the Diptera. Anopheles gambiae (family: Culicidae) and Clogmia albipunctata (Psychodidae) both belong to the paraphyletic assemblage of the Nematocera. Drosophila melanogaster (Drosophilidae) and Episyrphus balteatus (Syrphidae) belong to the monophyletic cyclorrhaphan Brachycera (higher flies). The column of graphs on the left schematically shows the presence and expression patterns of maternal co-ordinate genes; graphs on the right show zygotically expressed gap gene domains (at the end of C14A, just before gastrulation; solid triangles), and the delayed appearance of the posterior Hb domain in C. albipunctata (after gastrulation; triangle with dashed outline). X-axes represent the antero-posterior embryonic axis: anterior is to the left, posterior to the right. Maternal co-ordinate gene products: Bcd, Bicoid; Hb, Hunchback; Cad, Caudal. Gap gene products: Hb, Hunchback; Kr, Krüppel; Kni, Knirps; Gt, Giant; Tll, Tailless; Hkb, Huckebein. Fly images from the Encyclopedia of Life (http://www.eol.org), photographers: A. gambiae, Muhammad Mahdi Karim; C. albipunctata, Gail; D. melanogaster, André Karwath; E. balteatus, Malcolm Storey. All images under creative commons license.