Patterns of parasite species richness and abundance observed in fish hybrids. (A) F1 hybrids result from the crossing of two genetically divergent parental species. Higher species richness but lower parasite abundance are observed in F1 hybrids when compared to parental species; (B) Backcross hybrids result from the crossing of F1 hybrids and one or the other parental species. Parasite species richness is higher in backcross hybrids when compared to the parental species involved in a crossing, but is not different when compared to F1 hybrids. Parasite abundance in backcross hybrids is similar to that in parental species involved in a crossing; however, backcross hybrids are more infected by host-specific parasites associated with a parental species involved in a crossing (orange in the left backcrossing scenario and blue in the right backcrossing scenario).