Alternative scenarios concerning the evolution of the DSL ligands (Delta, Serrate and Jagged) in Metazoa, based on the phylogenetic hypothesis of . The EGF+VWC association found in the genome of Trichoplax may be considered either as specific to the placozoan lineage (scenario I) or as an intermediate step involved in the subsequent formation of Jagged/Serrate (scenario II). Domains are represented in different colours as indicated in the figure inset (signal peptide and transmembrane domain are excluded for clarity of presentation). Red and green lines indicate proposed occurrence period of the events.
Gazave et al. BMC Evolutionary Biology 2009 9:249 doi:10.1186/1471-2148-9-249