Molecular assessment of trematode co-infection and intraspecific competition in molluscan intermediate hosts

► SNP-based qPCR to detect and distinguish competing S. mansoni strains. ► Accurately identify the outcome of trematode co-exposure. ► Less than half of infections following co-exposure established by both strains. ► Quantify strain-specific productivity to show evidence of parasite competition. ► Molecular tool for empirical assessments of coevolutionary theory.