What factors explain the geographic range of mammalian parasites?

Free-living species vary substantially in the extent of their spatial distributions. However, distributions of parasitic species have not been comprehensively compared in this context. We investigated which factors most influence the geographic extent of mammal parasites. Using the Global Mammal Parasite Database we analyzed 17,818 individual geospatial records on 1,806 parasite species (encompassing viruses, bacteria, protozoa, arthropods, and helminths) that infect 396 carnivore, ungulate, and primate host species. As a measure of the geographic extent of each parasite species we quantified the number and area of world ecoregions occupied by each. To evaluate the importance of variables influencing the summed area of ecoregions occupied by a parasite species, we used Bayesian network analysis of a subset (n=866) of the parasites in our database that had at least two host species and complete information on parasite traits. We found that parasites that covered more geographic area had ...