Figure 5. Widespread gene duplication in an ancestor of the pea aphid, as suggested by the frequency distribution of synonymous
divergence (dS) between pairs of recent paralogs (Reciprocal Best Hits) within pea aphid, honey bee, andDrosophila. Vertical dotted
lines show the estimated average dS between orthologs from different aphid species. 1: A. pisumandMyzus persicae(two species of the tribe
Macrosiphini), mean dS = 0.25; 2:A. pisumandAphis gossypii(tribe Aphidini), mean dS = 0.35 (estimates from [128]). Paralogs resulting from ancient
duplications (dS.1.5) are also abundant in all three genomes (1,449 pairs in aphid, 1,726 in drosophila, 1,010 in bee; not shown).
doi:10.1371/journal.pbio.1000313.g005