Fig. 1

Genome annotation and evolution of W. pigra compared with H. robusta and H. medicinalis. A Phylogenetic analysis of leech species by Maximum Likelihood method based on COI genes. Highlighted with red dots correspond to three leech species compared with in our study. Posterior probabilities are assigned to the node; B the predicted protein-coding genes with matching entries in the three popular public databases; C the Venn diagram showed the orthologous genes between W. pigra and H. medicinalis (top panel), and between W. pigra and H. robusta (bottom panel); D Gene expansion and contraction in the W. pigra genome. The number of expanded (+) and contracted (-) gene families are shown along branches and nodes. E the Venn diagram showed the number of expanded and contracted gene families between W. pigra and H. medicinalis, and between W. pigra and H. robusta