Evolutionary gene coexpression networks. (A) Gene expression levels were measured across lines of C. elegans that diverged from a common ancestor. Relative expression levels across five MA lines (41, 24, 83, 99, N2) are shown for six genes. (B) Relative levels of gene expression across lines were compared for all pairs of genes using the Pearson correlation coefficient as shown here for genes B0024.11 × 3T27AS8.2. (C) In the evolutionary gene coexpression networks, genes are represented as nodes and gene pairs with r-values above the threshold cut-off are linked by edges.