Host Breadth of Parasites in Ungulates and Carnivores

Emili Price, a student from Winthrop University, worked with Drs. Patrick Stephens and John Gittleman in the Odum School of Ecology to look at host breath of parasites in ungulates and carnivores.

Emili Price1, Patrick R. Stephens2, John L. Gittleman2

1. Winthrop University, Rock Hill, South Carolina

2. Odum School of Ecology, University of Georgia, Athens, Georgia

Most parasites infect multiple hosts, but few studies have focused on characteristics of hosts and parasites that may cause differences in the host breadth. We investigated two facets of host breadth: variation in the number of host species different parasite species infect and the similarity of parasite communities among host species (i.e., overlap in the parasite species that infect different pairs of host species).  We first tested for the effects of parasite transmission mode and taxonomic identity on host breadth among parasites of ungulates and carnivores using a number of definitions of host breadth, and using several methods to try and correct for differences in sampling effort among parasite species. We found that viruses and sexually transmitted parasites infect significantly more hosts than other types of parasites in ungulates regardless of the estimate of host breadth considered.  We also found that viruses and vertically transmitted parasites infect significantly more hosts than other types of parasites among ungulate parasites that infect at least two hosts.  Finally, among carnivore parasites with two or more hosts, we found that parasites transmitted via feces infect significantly more hosts than other types of parasites.  We next investigated the effect of phylogenetic distance, differences in mass, and the geographic overlap among ungulate host species on parasite community similarity. All three variables showed statistically significant correlations with parasite overlap regardless of whether Jaccard’s or the corrected Jaccard’s index was used to measure parasite overlap among hosts.  However, geographic range area overlap and phylogenetic relatedness explained much more variation than differences in body mass among hosts.  Our results were almost identical when we restricted consideration to viruses, save that mass was an even weaker predictor of overlap.  Finally, we tested to see whether carnivore species that prey on ungulates are infected by more ungulate parasites than those that do not. We found that carnivore species that prey upon ungulates were infected by on average twice as many ungulate parasites than carnivores that specialize on different prey items.

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