Spatial Patterns of Host Species’ Transmission Dominance on the National Bison Range

Talk Abstract

Robert L. Richards (1), John M. Drake (1), and Vanessa O. Ezenwa (1,2)

(1) Odum School of Ecology, University of Georgia (2) Department of Infectious Diseases, University of Georgia

When parasites infect multiple host species, hosts that contribute disproportionately to transmission are common. These “transmission dominant” species are, by definition, important to transmission dynamics and often targets for parasite control measures. Here we examine how patterns of transmission dominance vary through space and across a suite of shared parasite species. We used fecal egg counts and DNA-barcoding identification to quantify each of 6 large ungulate host species’ contribution to environmental Force of Infection (FOI) of 7 parasitic worms at the National Bison Range, Montana, USA. Our non-parametric rank-order Friedman Tests show that hosts significantly differ in their transmission dominance rank across the 7 parasite species. Post-hoc analyses emphasize that it is the identity of the most dominant (Bison bison and Cervus canadensis) and least dominant (Antilocapra americana) which drive this relationship. We then fit plug-and-play species distribution models to presence data and predict presence probability across the range. Using these presence probabilities along with our species’ contribution metrics we predict the relative contribution of each host species to the FOI of parasite species at a 30m scale. While host species significantly differ in their transmission dominance rank across much of the range, the actual identities of the most dominant hosts tend to differ regionally for 3 parasite species. These results suggest that efforts to target single transmission dominant hosts for community-wide disease control may be effective across multiple parasites at certain spatial scales. Variation in space usage by hosts across broader distributions may, however, require differentially targeted control efforts.