title: Spatial parasite transmission, drug resistance, and the spread of rare genes.
abstract: The transmission of many parasitic worms involves aggregated movement between hosts of "packets" of infectious larvae. We use a generic metapopulation model to show that this aggregation naturally promotes the preferential spread of rare recessive genes, compared with the expectations of traditional nonspatial models. A more biologically realistic model also demonstrates that this effect could explain the rapid observed spread of recessive or weakly dominant drug-resistant genotypes in nematode parasites of sheep. This promotion of a recessive trait arises from a novel mechanism of inbreeding arising from the metapopulation dynamics of transmission.
authors.affiliation: Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, United Kingdom. cornell@zoo.cam.ac.uk
authors.forename: S J
authors.initials: SJ
authors.lastname: Cornell
authors.forename: V S
authors.initials: VS
authors.lastname: Isham
authors.forename: G
authors.initials: G
authors.lastname: Smith
authors.forename: B T
authors.initials: BT
authors.lastname: Grenfell
mesh_terms: D000818:Animals; D004351:Drug Resistance / Q000235:genetics; D005799:Genes, Dominant; D017238:Genes, Helminth; D005808:Genes, Recessive; D006790:Host-Parasite Interactions / Q000235:genetics; D008954:Models, Biological; D009348:Nematoda / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity; D010272:Parasitic Diseases / Q000188:drug therapy / Q000469:parasitology / Q000635:transmission*; D012756:Sheep; D012757:Sheep Diseases / Q000188:drug therapy / Q000469:parasitology / Q000635:transmission; D014253:Trichostrongylosis / Q000188:drug therapy / Q000469:parasitology / Q000635:transmission / Q000662:veterinary