Components influencing parasitism by Dadaytrema oxycephala (Digenea: Cladorchiidae) in Neotropical fish.

The components that mold the structure of parasitic fauna are used as objects of study in an attempt to find patterns in their distribution. It is known that phylogeny (represented by specificity), host ecological traits (for example, feeding habits, position of the water column, reproductive strategies, body size, and age), and the environment affect the distribution and occurrence of parasites. In tropical regions, digeneans show high diversity, and the species Dadaytrema oxycephala is known to parasitize a wide range of host species. In this context, the objective of the present study is to analyze the components that affect the occurrence of D. oxycephala in Neotropical fish. We used data from the literature that contained the abundance of this parasite, as well as the geographic location and host species, and evaluated the influence of ecological traits, specificity, and latitude on parasite abundance, using a generalized linear mixed model (GLMM). The abundance of D. oxycephala can be explained by trophic level and position in the water column and latitude. However, coevolutionary processes are also extremely important, and the distribution of this parasite was not equal, showing high abundance for the genus Piaractus, which are the preferred hosts, even if the parasite is considered generalist. In short, host ecological traits are the important components in the distribution and occurrence of D. oxycephala, as well as the latitude.