Figure 2.—

Combined phylogenetic analysis of RAG1 and RAG2 paralogs. Nodes with <95% posterior probability or that were inconsistent between the α and β lineages are collapsed, asterisks indicate RAG1 paralogs for which expression was confirmed, and linked X. laevis RAG1 and RAG2 paralogs (Greenhalgh et al. 1993) are connected by a line. Degenerate paralogs are in red and missing paralogs are in gray. Numbers 1–9 indicate the minimum independent degenerations of RAG1 mentioned in the text, and 10, 11, and 12 refer to degeneration of RAG2 lineage α, degeneration X. andrei RAG2 paralog β2, and a suspected ancestral deletion spanning paralogs of RAG1 and RAG2, respectively.