No abstract

This is a repository copy of Fluctuating asymmetry, parasitism and reproductive fitness in two species of gammarid crustacean.

No abstract

19The Trematoda are a group of phylogenetically diverse metazoan parasites that 20 exhibit complex life cycles that often pass through invertebrate and vertebrate hosts. 21Some trematodes influence their host's behaviour to benefit transmission. Their 22 parasitic influence may impact host population size by inhibiting an individual's 23 reproductive capacity. 24We assessed the impact of infection by Podocotyle atomon on the reproductive 25 behaviour and fecundity of its amphipod intermediate host, Gammarus zaddachi, 26 using laboratory and field studies. Parasite prevalence was high in the field, with 27 males more likely to be infected (prevalence in males 64%, in females 39%). Males 28 also suffered a higher parasite burden than females. Infected females were less 29 active, but we found no evidence for a reduction in female reproductive success. 30Infected females also had comparable pairing success to uninfected females. In 31 males, infection reduced survival and fecundity, with mortality being highest, and 32 sperm numbers lowest, in heavily infected individuals. Trematode parasites are 33 sometimes associated with altered host fecundity, but studies often lack the relevant 34 experimental data to explore the evolution of the trait. We discuss this among 35 information specific to the effect of P. atomon infection in G. zaddachi. 36 37