title: Assortative pairing in Gammarus insensibilis (Amphipoda) infected by a trematode parasite.
abstract: We have investigated the influence of Microphallus papillorobustus (Trematoda) on the reproductive biology and mating patterns of its intermediate host Gammarus insensibilis (Amphipoda). Infected Gammarus species show altered behaviour which renders them more susceptible to predation by Charadriiform birds, the parasite's definitive hosts. In a natural population of G. insensibilis, mean parasite intensity was higher for unpaired individuals than for paired individuals. Fecundity was reduced in infected amphipods. Size-assortative pairing was significant, although infected males were found with smaller females compared to uninfected males of the same size. There was also a positive assortative pairing by parasitic prevalence. Vertical segregation between infected and uninfected individuals, male-male competition for access to uninfected females, and female choice may explain assortative mating for prevalence. This study provides the first empirical evidence that parasites can have a direct effect on patterns of mating in gammarids.
authors.affiliation: Laboratoire de Parasitologie Comparée (URA 698, CNRS), Université Montpellier II, place Eugène Bataillon, F-34095, Montpellier, Cedex 05, France.
authors.forename: F
authors.initials: F
authors.lastname: Thomas
authors.affiliation: Laboratoire de Parasitologie Comparée (URA 698, CNRS), Université Montpellier II, place Eugène Bataillon, F-34095, Montpellier, Cedex 05, France.
authors.forename: F
authors.initials: F
authors.lastname: Renaud
authors.affiliation: Laboratoire de Parasitologie Comparée (URA 698, CNRS), Université Montpellier II, place Eugène Bataillon, F-34095, Montpellier, Cedex 05, France.
authors.forename: J M
authors.initials: JM
authors.lastname: Derothe
authors.affiliation: Laboratoire de Parasitologie Comparée (URA 698, CNRS), Université Montpellier II, place Eugène Bataillon, F-34095, Montpellier, Cedex 05, France.
authors.forename: A
authors.initials: A
authors.lastname: Lambert
authors.affiliation: Laboratoire de Parasitologie Comparée (URA 698, CNRS), Université Montpellier II, place Eugène Bataillon, F-34095, Montpellier, Cedex 05, France.
authors.forename: T
authors.initials: T
authors.lastname: De Meeüs
authors.affiliation: Station Biologique de la Tour du Valat, Le Sambuc, F-13200, Arles, France.
authors.forename: F
authors.initials: F
authors.lastname: Cézilly
keywords: Gammarus insensibilis; Host reproductive success; Microphallus papillorobustus; Parasitism; Trematode