Print PageParasites can alter the physiology and ecology of their hosts and will likely also affect their hosts’ interaction with co-existing species such as predators or competitors. For instance, parasitism may indirectly alter community structure by weakening an otherwise superior competitor or by increasing its susceptibility to predation. Here, we test the effect of the presence versus absence of a specialist parasite on two competing fishes that have co-evolved in a local community. Killifish (Rivulus hartii) are ubiquitous to all reaches of Trinidadian streams and are the only species of fish present in the most up-stream regions. Other Rivulus populations have evolved under the presence of a competitor: the guppy (Poecilia reticulata). In addition, Rivulus can co-occur with guppies that are either free of, or infected with, the ectoparasitic monogenean worm Gyrodactylus, and these local patterns are repeated across different streams in Trinidad. We compared the ecology of invertebrate fauna (e.g. diversity, abundance, size distribution), as well as geometric-morphometric and life history analysis of both fish species in the three community complexes (Rivulus-only, Rivulus-guppy, Rivulus-guppy-Gyrodactylus) of four different streams in Trinidad.
Results/Conclusions
We evaluate the indirect effects of Gyrodactylus, via guppy infection, on: a) Rivulus traits in light of the morphological and life history differences between Rivulus from the three communities, and b) the invertebrate fauna, through mediating the interaction between Rivulus and guppies.
