Figure 2
From: Divergence of imprinted genes during mammalian evolution
Complementary divergence. The orthologs of single copy genes (s) are more diverged than the orthologs of genes that possess paralogs. Regarding paralogous pairs of biallelically expressed genes (b1, b2), one is usually more diverged than the other. If an imprinted gene (a1i) has a paralog (a2), the imprinted gene itself is in most cases the more divergent one.