Approximate fraction of the genome occupied by introns in selected extant eukaryotic taxa and in a hypothetical pre-LECA eukaryote. For each taxon, the genome with the highest intron content (as in Figure 2) was chosen. The data are from the National Center for Biotechnology Information genome division (http://www.ncbi.nlm.nih.gov/Genomes/). (This figure appears in color in the online version of Journal of Heredity.)