Interspecies copy number variations of nematode Polintons. Bar graphs (right panel) showing average copy numbers per genome of full-length pPolB1-class and pPolB2-class Polintons in selected Nematoda genomes where the species can be placed on a current phylogenetic tree based on recent analyses (Ahmed et al. 2022; Lee et al. 2023). Note that several species that have not yet been placed on the tree are not shown here; all information for species (placed and not) is shown in supplementary table S1, Supplementary Material online.