Predicted evolutionary pathway for hatching enzyme and egg envelope protein in the euteleostean lineage. The phylogram of euteleosts was simplified from the mitogenomic phylogeny of fishes [30, 31]. Divergence time was according to Setiamarga et al. , and the lineages drawn with dotted lines are hypothetical. Amino acid residues of the ancestral P2 site and those of positions 74, 91, 135, and 183 on ancestral LCEs are shown in the boxes at the nodes. The residues for the ancestor of neoteleosts are colored black, and the residues substituted during evolution are colored red. P2 site preferences of ancestral LCEs of Neoteleostei (ancNeotLCE), Atherinomorpha (ancAtheLCE), Beloniformes (ancBeloLCE), and Oryziinae (ancOryzLCE) are shown at each node.