title: Coexistence of three microsporidia parasites in populations of the freshwater amphipod Gammarus roeseli: evidence for vertical transmission and positive effect on reproduction.
abstract: We investigated the prevalence, transmission mode and fitness effects of infections by obligatory intracellular, microsporidian parasites in the freshwater amphipod Gammarus roeseli. We found three different microsporidia species in this host, all using transovarial (vertical) transmission. All three coexist at different prevalences in two host populations, but bi-infected individuals were rarely found, suggesting no (or very little) horizontal transmission. It is predicted that vertically-transmitted parasites may exhibit sex-specific virulence in their hosts, or they may have either positive or neutral effects on host fitness. All three species differed in their transmission efficiency and infection intensity and our data suggest that these microsporidia exert sex-specific virulence by feminising male hosts. The patterns of infection we found exhibit convergent evolution with those of another amphipod host, Gammarus duebeni. Interestingly, we found that infected females breed earlier in the reproductive season than uninfected females. This is the first study, to our knowledge, to report a positive effect of microsporidian infection on female host reproduction.
authors.affiliation: Equipe Ecologie Evolutive, UMR CNRS 5561 Biogéosciences, Université de Bourgogne, 6 Boulevard Gabriel, 21000 Dijon, France.
authors.forename: Eleanor R
authors.initials: ER
authors.lastname: Haine
authors.forename: Emilie
authors.initials: E
authors.lastname: Brondani
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Hume
authors.forename: Marie-Jeanne
authors.initials: MJ
authors.lastname: Perrot-Minnot
authors.forename: Maria
authors.initials: M
authors.lastname: Gaillard
authors.forename: Thierry
authors.initials: T
authors.lastname: Rigaud
mesh_terms: D000818:Animals; D001483:Base Sequence; D003445:Crustacea / Q000469:parasitology* / Q000502:physiology; D005260:Female; D006790:Host-Parasite Interactions; D018445:Infectious Disease Transmission, Vertical; D008297:Male; D016815:Microsporea / Q000235:genetics; D016881:Microsporidiosis / Q000635:transmission*; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D012098:Reproduction; D012758:Shellfish / Q000469:parasitology*
chemical_list: D012336:RNA, Ribosomal, 16S