Figure 3From: The expansion of the metazoan microRNA repertoireExamples of microRNA gene duplication histories. (a) Gene tree and most plausible reconstructed history of the mir9 cluster. The fourth member of the cluster, mir-306, evolves rapidly in flies. Its homology with mir-9/mir-79 is likely but this hairpin might also have evolved de novo. (b) The two most plausible reconstructions for the history of the mir-23 cluster. Scenario (1) postulates four paralogs in the ancestral vertebrate, where, presumably after the first duplication, one lineage either lost or gained mir-27 in the middle position of the cluster. Subsequently, in this scenario one copy of the three-membered cluster was lost in actinopterygians, while the two-membered clusters were lost in tetrapoda. Scenario (2) postulates three paralogs in the ancestral vertebrate and the independent loss of the mir-27 in two distinct clusters in the teleosts. (c) Duplication history of the mir-130 cluster reconstructed from genomic position information and the gene tree.Back to article page