title: Digging for answers: contributions of density- and frequency-dependent factors on ectoparasite burden in a social mammal.
abstract: Due to the density-dependent nature of parasite transmission parasites are generally assumed to constrain the evolution of sociality. However, evidence for a correlation between group size and parasite burden is equivocal, particularly for mammals. Host contact rates may be modified by mobility of the host and parasite as well as social barriers. In the current study, we used the common mole-rat (Cryptomys hottentotus hottentotus), a social subterranean rodent, as a model system to investigate the effect of host density and frequency of contact rates on ectoparasite burdens. To address these factors we used a study species that naturally varies in population densities and intergroup contact rates across its geographic range. We found that ectoparasite prevalence, abundance and species richness decreased with increasing host density at a regional scale. At the same time, measures of parasite burden increased with intergroup contact rates. Ectoparasite burdens decreased with colony size at the group level possibly as a result of increased grooming rates. Equating group size with population density might be too simplistic an approach when assessing parasite distributions in social mammals. Our data suggest that frequency-dependent mechanisms may play a much greater role at a population level than density-dependent mechanisms in determining parasite distributions in social species. We suggest that future studies should explicitly consider behavioural mechanisms that may affect parasite distribution.
authors.affiliation: Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa.
authors.forename: Elizabeth K
authors.initials: EK
authors.lastname: Archer
authors.affiliation: Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa.
authors.forename: Nigel C
authors.initials: NC
authors.lastname: Bennett
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
authors.forename: Chris G
authors.initials: CG
authors.lastname: Faulkes
authors.affiliation: Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa. hlutermann@zoology.up.ac.za.
authors.forename: Heike
authors.identifier: http://orcid.org/0000-0002-7521-2302
authors.initials: H
authors.lastname: Lutermann
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D005075:Biological Evolution; D008297:Male; D008322:Mammals / Q000469:parasitology*; D019577:Mole Rats / Q000469:parasitology; D010271:Parasites / Q000254:growth & development*; D010272:Parasitic Diseases / Q000469:parasitology / Q000635:transmission*; D011156:Population Density; D012919:Social Behavior
keywords: Cryptomys; Ectoparasite; Group size; Parasite transmission; Sociality