title: Dispersal in a parasitic worm and its two hosts: consequence for local adaptation.
abstract: Characterizing host and parasite population genetic structure and estimating gene flow among populations is essential for understanding coevolutionary interactions between hosts and parasites. We examined the population genetic structure of the trematode Schistosoma mansoni and its two host species (the definitive host Rattus rattus and the intermediate host Biomphalaria glabrata) using microsatellite markers. Parasites were sampled from rats. The study was conducted in five sites of the Guadeloupe Island, Lesser Antilles. Mollusks display a pattern of isolation by distance whereas such a pattern is not found neither in schistosomes nor in rats. The comparison of the distribution of genetic variability in S. mansoni and its two host species strongly suggests that migration of parasites is principally determined by that of the vertebrate host in the marshy focus of Guadeloupe. However, the comparison between genetic differentiation values in schistosomes and rats suggests that the efficacy of the schistosome rat-mediated dispersal between transmission sites is lower than expected given the prevalence, parasitic load and migration rate of rats among sites. This could notably suggest that rat migration rate could be negatively correlated to the age or the infection status of individuals. Models made about the evolution of local adaptation in function of the dispersal rates of hosts and parasites suggest that rats and mollusks should be locally adapted to their parasites.
authors.affiliation: GEMI, Equipe ESS, UMR-2724 CNRS-IRD, centre IRD, 34394 Montpellier Cedex 5, France. fp235@mole.bio.cam.ac.uk
authors.forename: Franck
authors.initials: F
authors.lastname: Prugnolle
authors.forename: André
authors.initials: A
authors.lastname: Théron
authors.forename: Jean Pierre
authors.initials: JP
authors.lastname: Pointier
authors.forename: Roula
authors.initials: R
authors.lastname: Jabbour-Zahab
authors.forename: Philippe
authors.initials: P
authors.lastname: Jarne
authors.forename: Patrick
authors.initials: P
authors.lastname: Durand
authors.forename: Thierry
authors.initials: T
authors.lastname: de Meeûs
mesh_terms: D000818:Animals; D001483:Base Sequence; D003710:Demography; D004777:Environment; D006580:Genetic Carrier Screening; D014644:Genetic Variation; D005828:Genetics, Population; D005843:Geography; D019430:Guadeloupe; D006790:Host-Parasite Interactions; D018895:Microsatellite Repeats / Q000235:genetics; D008954:Models, Biological; D008969:Molecular Sequence Data; D051381:Rats / Q000235:genetics* / Q000469:parasitology; D012550:Schistosoma mansoni / Q000235:genetics*; D017422:Sequence Analysis, DNA; D012908:Snails / Q000235:genetics* / Q000469:parasitology