Fig. 6

GC content of exons and introns in order. The seven species are displayed in a phylogenetic order with unscaled branch length. The four columns represent the genes with two, six, ten, and 20 exons, respectively. Exons and introns are displayed in order (from 5’ to 3’). Exons are in red and introns are in blue. The differential GC content between exons were measured by Wilcoxon rank sum tests, and P < 0.05 was regarded as significant