Four example patterns of normalized gene expression. The darker line represents one copy within a pair and the lighter line represents the other copy. Gene identification numbers (RSP), homolog type (O or I), and percent divergence of each copy in the pair are given at the top of each graph. Each graph is an example from the previously defined four expression classifications: (A) High cosine (>0.5) with low divergence (≤50%), (B) high cosine with high divergence (>50%), (C) low cosine (≤0.5) with low divergence, and (D) low cosine with high divergence. It is evident that gene-pairs with high cosine have similar expression patterns while those with low cosine have dissimilar expression patterns.