Figure 3

Histogram showing the f_2Y (a) and f_2R (b) values of all mouse:rat intertaxa homolog pairs containing 50 or more characters. The peak centered at ca. 0.88 (a) and ca. 0.90 (b) reflect true orthologs. Pairs with f₂ values near 0.53 diverged so long ago that the silent sites have equilibrated.