Parasites and Host Geographic Range as Illustrated by Waterfowl

Abstract

Several papers have suggested that host species with larger geographic ranges tend to harbour a greater number of parasite species than those with smaller ranges. However, few of these investigations have dealt quantitatively with problems related to host sampling and/or phylogeny. This paper describes a positive relationship between the number of helminth parasite species per host and host species geographic range in Holarctic waterfowl. The analysis controls for the effects of differential sampling of host species and for the effects of taxonomic association. Neither host body size, population size, population density, nor social tendency correlate significantly with the number of parasite species per host corrected for number of hosts examined, and therefore association with these variables is unlikely to confound the relationship between parasites and host geo-