Comparison of the GC
between the species and among the gene groups. Histograms show mean ± SEM of GC3. The rat snake and chicken orthologs are grouped as described in text: group 1) genes located on macrochromosomes in both species, group 2) genes located on microchromosomes in both species, and group 3) genes located on macrochromosomes in the snake and on microchromosomes in the chicken. Because only three genes were classified into the 4th group, indicated by blue dots in Figure 4B, the GC3 of this group was not compared statistically and thus omitted from this figure. Horizontal lines above bars show differences. Significances for comparison between species (black lines) and for comparison between groups (blue and red lines) are examined by Mann-Whitney’s U-test and the Kruskal-Wallis test with Dunn's post test, respectively. *P<0.05, **P<0.01, ***P<0.001 and n.s., not significant.