Endoparasite species richness of New Caledonian butterfly fishes: host density and diet matter

Ecological factors may influence the number of parasites encountered and, t hus, parasite species richness. These factors include diet, gregarity, cons pecific and total host density, habitat,body size, vagility, and migration. One means of examining the influence of these factors on parasite species richness is through a comparative analysis of the parasites of different, b ut related, host species. In contrast to most comparative studies of parasi te species richness of fish, which have been conducted by using data from t he literature, the present study uses data obtained by the investigators. C oral reef fishes vary widely in the above ecological factors and are freque ntly parasitized by a diverse array of parasites. We, therefore, chose to i nvestigate how the above ecological factors influence parasite species rich ness in coral reef fishes. We investigated the endoparasite species richnes s of 21 species of butterfly fishes (Chaetodontidae) of New Caledonia. We m apped the diet characters on the existing butterfly fish phylogeny and foun d that omnivory appears to be ancestral. We also mapped the estimated endop arasite species richness, coded from low to high parasite species richness, on the existing butterfly fish phylogeny and found that low parasite speci es richness appears to be associated with the ancestral state of omnivory. Different dietary and social strategies appear to have evolved more than on ce, with the exception of obligate coralivory, which appears to have evolve d only once. Finally, after controlling for phylogenetic relationships, we found that only the percentage of plankton in the diet and conspecific host density were positively correlated with endoparasite species richness.