Figure 3.

Fitch diagram [29] illustrating the origin and distribution of ortholog and paralogs of trpD in cyanobacteria. Paralogs, originating by gene duplication events (Dp1 and Dp2), track back to a horizontal line, whereas orthologs, originating by speciation (Sp1, Sp2, Sp3 and Sp4), track back to an inverted Y. The six trpD genes of Nostoc (Npu) and Anabaena (Asp) comprise a paralog set, and each of those comprises a four-member ortholog set with respect to the trpD genes from P. marinus (Pmu), Synechococcus sp. (Syn), and Synechocystis sp. (Ssp).