Data for the Gopko et al. paper ''Does phylogenetic relatedness imply similar manipulative ability in parasites?

Many parasites can alter the behavior of their hosts in a manner that is beneficial for the parasite (parasitic manipulations). Obviously, examples of non-manipulative parasites also exist, however, their number might be underestimated because of the publication bias. Trematodes from the Diplostomidae family infecting fish eyes are often considered manipulators. However, only one species (Diplostomum pseudospathaceum) of this family has been shown to do so under controlled laboratory conditions. We experimentally studied whether another common diplostomid species (Tylodelphys clavata) manipulated the host defensive behavior using salmonids (Salvelinus malma) reared and infected in the laboratory. We tested fish activity, depth preference, and dip net avoidance (common fish defensive traits) under different light conditions. Although the experimental design was identical to those used earlier for D. pseudospathaceum, no manipulative abilities were detected inT. clavata. Infected fish did not differ from control in the expression of the defensive behavioral traits tested. Interestingly, fish activity was confounded with fish size in control but not in infected fish, however, this pattern does not seem to be a manipulation. Our results show that even closely related parasites occupying similar habitat niches can dramatically differ in their ability to manipulate host behavior.