FIGURE 4. Gene family evolution. (a) The proportion of various
gene classes among nine species. (b) Expansion and contraction of gene
families in nine species. A phylogenetic tree was constructed based on
523 single-copy orthologous genes using O. sativa as the
outgroup. Pie diagrams on each branch of the tree represent the
proportion of genes undergoing gain (green) or loss (red) events, the
numbers near the nodes represent number of gene families expanded or
contracted. The scale on the X axis shows the estimated divergence time
for nodes.