Fig. 5

Ultrametric tree of the studied bee species indicating the significant gene family changes in each node. I = gene family expansion events (increase), D = gene family contraction events (decrease). Colors (from yellow to purple) indicate the proportion of changes that were due to gene family expansion, i.e., the expansion ratio is given by E = (D × 100) / (I + D). Nodes experiencing more gene family contractions are yellow while a larger proportion of expansion events is illustrated in purple. M. bicolor is highlighted in bold