Enumeration of gene constellations in the Drosophila genome. (A) Numbers and percentages of genes that resulted from the application of the scheme depicted in Figure 1. Duplicated genes are shown as pie slices. (B) Plot of gene abundance for each constellation versus genomic distances over which co-clustering genes have shown correlations in expression (transcriptional territories; range 20-200 kb, median 100 kb [11, 13]). Gene abundances prior to and following removal of gene duplicates are shown as solid lines and dashed lines, respectively.