Fig. 1.

A. A phylogeny of metazoan evolution. This tree depicts likely relationships of the species used in this study within the metazoan subkingdom. B. Distribution of Wnt and Frizzled genes throughout the metazoan sub-kingdom. An X designates the absence of a member of that subfamily in the corresponding annotated genome. Question marks underline uncertainty of the orthology. The absence of information indicates that no corresponding orthologs have been reported in these species for which genomic databases are not yet available. For lineages other than the Echinodermata, data derive from Hino et al., 2003; Holland, 2002; Hotta et al., 2003; Jockusch and Ober, 2000; Katoh and Katoh, 2005; Kusserow et al., 2005; Lee et al., 2006; Leveugle et al., 2004; Maloof et al., 1999; Marsal et al., 2003; Nusse, 2001; Prud’homme et al., 2002; and Schubert et al., 2000).