Amplification of ATon-I and ATon-II families. (A) Divergence distribution of ATons. x-axis, divergence of an ATon member from its consensus sequence; y-axis, number of ATon elements. (B) Phylogenetic tree of ATon-I family. Letters “a” to “e”, five subclades. (C) Phylogenetic tree of ATon-2 family. Letters “a” to “i”, nine subclades. Green highlights, subclades with large numbers of identical elements.