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In eukaryotes, the primary components of the ribosome are encoded by multicopy nuclear ribosomal RNA (rRNA) genes: 28/26S, 18S, 5.8S, and 5S. Copies of these genes are typically localized within tandem arrays and homogenized within a genome. As a result, nuclear rRNA gene families have become a paradigm of concerted evolution. In filamentous fungi of the subphylum Pezizomycotina, 5S rRNA genes exist as a large and dispersed multigene family, with between 50 and 100 copies per genome. To determine whether these genes defy the concerted evolution paradigm, we examined the patterns of evolution of these genes by using sequences from the complete genomes of four species. Analyses of these sequences revealed (i) multiple 5S gene types within a genome, (ii) interspecies clustering of gene types, (iii) multiple identical gene types shared among species, (iv) multiple pseudogenes within a …