Fig. 2

Phylogenetic tree and the proportion of gene family clusters based on ten beetle species. The phylogenetic tree was constructed based on 1751 single-copy orthologs shared among ten beetle species. All nodes have 100% bootstrap support. Branches are labeled with the number of gene family expansions (+) and contractions (−) that occurred on that lineage. These genes were categorized into five groups: one-copy (single copy orthologous genes in common gene families); two-copy (two copy orthologous genes in common gene families), three-copy, four-copy and more than four-copy; uncluster (genes that do not cluster to any families)