title: Linking parasite populations in hosts to parasite populations in space through Taylor's law and the negative binomial distribution.
abstract: The spatial distribution of individuals of any species is a basic concern of ecology. The spatial distribution of parasites matters to control and conservation of parasites that affect human and nonhuman populations. This paper develops a quantitative theory to predict the spatial distribution of parasites based on the distribution of parasites in hosts and the spatial distribution of hosts. Four models are tested against observations of metazoan hosts and their parasites in littoral zones of four lakes in Otago, New Zealand. These models differ in two dichotomous assumptions, constituting a 2 × 2 theoretical design. One assumption specifies whether the variance function of the number of parasites per host individual is described by Taylor's law (TL) or the negative binomial distribution (NBD). The other assumption specifies whether the numbers of parasite individuals within each host in a square meter of habitat are independent or perfectly correlated among host individuals. We find empirically that the variance-mean relationship of the numbers of parasites per square meter is very well described by TL but is not well described by NBD. Two models that posit perfect correlation of the parasite loads of hosts in a square meter of habitat approximate observations much better than two models that posit independence of parasite loads of hosts in a square meter, regardless of whether the variance-mean relationship of parasites per host individual obeys TL or NBD. We infer that high local interhost correlations in parasite load strongly influence the spatial distribution of parasites. Local hotspots could influence control and conservation of parasites.
authors.affiliation: Laboratory of Populations, The Rockefeller University, New York, NY 10065; cohen@rockefeller.edu.|Laboratory of Populations, Earth Institute of Columbia University, New York, NY 10027.
authors.forename: Joel E
authors.identifier: 0000-0002-9746-6725
authors.initials: JE
authors.lastname: Cohen
authors.affiliation: Department of Zoology, University of Otago, Dunedin 9054, New Zealand.
authors.forename: Robert
authors.initials: R
authors.lastname: Poulin
authors.affiliation: Department of Zoology, University of Otago, Dunedin 9054, New Zealand.
authors.forename: Clément
authors.initials: C
authors.lastname: Lagrue
mesh_terms: D000818:Animals; D016010:Binomial Distribution; D003710:Demography / Q000379:methods*; D004463:Ecology; D006790:Host-Parasite Interactions / Q000502:physiology*; D006801:Humans; D008954:Models, Biological; D009520:New Zealand; D059208:Parasite Load; D010271:Parasites / Q000254:growth & development*; D011157:Population Dynamics
keywords: freshwater communities; parasite load; spatial distribution; synchrony; variance function