Opening the Doors of Parasitology Journals to Other Symbionts

Intimate symbiotic relationships between species (e.g., between a larger ‘host’ and a smaller ‘symbiont’) span the range from mutualism to parasitism. The nature of a symbiotic relationship is not an intrinsic trait of the species involved, but rather the outcome of their interaction. Many symbiont species move along the mutualism–parasitism continuum depending on the environmental conditions [1]. For instance, defensive symbionts act as mutualists when they clean hosts of parasites, but they may harm their hosts when there are no parasites to clean [2].