Fig. 2
Histogram of the distribution of selection parameter k values (exponent of dN/dS ratio, i.e., k in ωk) from RELAX analysis in the 2702 orthogroups. The values shown are for Coregonus and Salvelinus compared to the other five salmonid species and the outgroup (pike). The neutral expectation of k = 1 is shown as a vertical line. k values above 2 are omitted for visibility purposes in the above plot (416 orthogroups have k values above 2; the maximum possible k value is 50; see Additional file 1 for total set of k values)