Figure 1
From: Linking evolution of protein structures through fragments
Density chart showing the distribution of links between superfamilies based on fragment-pairs of length 30. The distributions for 'young' and 'old' superfamilies are shown separately, with younger fold having significantly fewer links (Wilcoxon unpaired test: p-value = 1.2e-09). Note that the distribution of links per superfamily is not normally distributed.