Relationships between genome sizes and paralog number. A and B) Diagnostic plots of absolute values of standardized independent contrasts in genome size (A) and number of paralogs (B) versus their standard deviations (square roots of sums of branch lengths) for Clade 1 (closed circles) and Clade 2 (open circles) cyanobacteria. The plots shows that contrasts within Clade 1 are, on average, larger in magnitude (Wilcoxon tests, two-tailed p < 0.0001). This indicates that genome sizes and gene-copy numbers have evolved at a higher rate in Clade 1 species. In A and B, a plus sign denotes the contrast between Clade 1 and Clade 2, which was excluded from the tests. C) Phylogenetically correct regression analysis through the origin of contrasts in number of paralogous gene copies vs. positivized contrasts in genome size for Clade 1. The plots show a strong positive correlation between genome size and number of duplicated genes (r = 0.691, two-tailed p < 0.0001).