Analysis of the draft gene set reveals that M. brevicollis possesses proteins containing domains characteristic of metazoan Notch (a, N1–N3) and hedgehog (b, H1 and H2). Some of these protein domains were previously thought to be unique to metazoans. The presence of these domains in separate M. brevicollis proteins implicates domain shuffling in the evolution of Notch and Hedgehog. Hh, hedgehog; N-hh, hedgehog N-terminal signalling domain; Hint, hedgehog/intein domain; TM, transmembrane domain; VWA, von Willebrand A domain. See Supplementary Note 3.6 for protein accession numbers and Supplementary Fig. 6 for identification of all displayed protein domains. Species names follow the convention from Fig. 1.