Size distribution of perfect duplicons in C. elegans genome. (a) Size distribution of all perfect duplicons in the C. elegans genome measured in number of genes. (b) Size distribution of all perfect duplicons in the C. elegans genome measured in kb. Each N value in the x-axis represent all those duplicons that fall in the range [N-1..N) kb. The y-axis represents the frequency in a logarithmic scale (base 10) of the frequency of a specific duplicon size. Thus, those bins with no visible bar mean that only one duplicon is observed for that particular value.