Figure 4. Lineage-specific gene expansions in the pea aphid.(A) Size distribution of the major lineage-specific groups of in-paralogs (i.e.,
paralogs resulting from duplications occurring after the split of the lineages leading to the pea aphid and the lousePediculus humanus). The y-axis
(logarithmic scale) represents the number of gene families with lineage-specific expansions of a given size (x-axis), as inferred from the pea aphid
phylome. (B) Maximum likelihood phylogenetic tree showing lineage-specific expansion of a family coding for Acetyl-CoA transporter. This expansion
has resulted in 19 paralogs in the pea aphid, whereas other insects and out groups included in the analysis possess only a single ortholog