Molecules infer origins of ectoparasite infrapopulations on tuna

► No Nasicola klawei infrapopulation was monophyletic by ITS1-SSCP analysis. ► AFLP profiles of 80-110 bands failed to support genomic monophyly of any N. klawei infrapopulation. ► Infrapopulations resulted from multiple oncomiracidial infections not from a colonizer producing auto-infecting progeny.