Figure 2.

Conservation and plasticity of platypus snoRNAs. Phylogenetic tree of mammals modified after Kriegs et al. (2006). (Black vertical bars) The conservation (platypus-specific, mammalian-specific, and presence in at least mammals plus birds) of the platypus snoRNAs. The numbers above the black bars represent the number of experimentally identified snoRNA orthologs that show clear presence or absence in the corresponding groups. The numbers in parentheses denote mammalian conserved loci for which no non-mammalian sequence information was accessible. (Gray bars) Examples of shifts from one potentially active paralog (a) to another potentially active paralog (b) at different genomic locations (the details are presented as Supplemental material). The snoRNA designations in the cDNA library are Oa1973, Oa2916, and Oa2364.