Conservation of transcript abundance between various species. (a) Scatter plot representing the abundance of the D. discoideum transcripts (x-axis, log10 scale) compared to their D. purpureum orthologs (y-axis, log10 scale). Each point represents the sum of read counts over the seven developmental time points. We divided the genes into three groups and indicated enriched Gene Ontology terms. Low abundance, <1,000 reads (green); intermediate abundance, 1,000 to 10,000 reads (blue); and high abundance, >10,000 reads (red). (b) We calculated the median gene abundance rank (y-axis, percentile) within five functional categories (indicated by the color code) in amoebae (D. discoideum and D. purpureum), mice (M. musculus), and yeast (S. cerevisiae), as indicated (x-axis). The asterisk indicates that only 21 genes represent this category in D. purpureum whereas the other species have >100 genes.