0000000000416619
AUTHOR
Stewart J. Plaistow
Variation in the risk of being wounded: an overlooked factor in studies of invertebrate immune function?
In invertebrates, wounding can trigger an immune response, and will often expose organisms to parasites and pathogens. Here we show that in the amphipod Gammarus pulex, wounding abundance is negatively correlated with PhenolOxidase activity (a major component of the invertebrate immune response), and that the occurrence and abundance of wounding is extremely high and varies significantly between five natural populations. In some populations the prevalence and abundance of wounds also varied between sexes. Given that, using and maintaining an efficient immune system is costly, we suggest that the frequency of wounding may be an important selective pressure influencing an organism's optimal i…
Patterns of intermediate host use and levels of association between two conflicting manipulative parasites.
For many parasites with complex life cycles, manipulation of intermediate host phenotypes is often regarded as an adaptation to increase the probability of successful transmission. This phenomenon creates opportunities for either synergistic or conflicting interests between different parasite species sharing the same intermediate host. When more than one manipulative parasite infect the same intermediate host, but differ in their definitive host, selection should favour the establishment of a negative association between these manipulators. Both Polymorphus minutus and Pomphorhynchus laevis exploit the amphipod Gammarus pulex as intermediate host but differ markedly in their final host, a f…
Energetically costly precopulatory mate guarding in the amphipod Gammarus pulex: causes and consequences
Precopulatory mate guarding (PCMG) is thought to have evolved as a male mating strategy in species in which female receptivity is limited to a short time. It is common among crustaceans, and energetic costs associated with PCMG are thought to promote size-assortative pairing in such species, although direct evidence is lacking. Using both field surveys and laboratory experiments, we assessed the energetic costs of PCMG in Gammarus pulex and investigated their possible causes. Energetic costs were measured as differences in lipid and glycogen reserves. In field-collected samples, size-corrected lipid and glycogen reserves of paired males were both significantly higher than those of unpaired …
The effect of the acanthocephalan parasite Pomphorhynchus laevis on the lipid and glycogen content of its intermediate host Gammarus pulex
Besides conspicuous changes in behaviour, manipulative parasites may also induce subtle physiological effects in the host that may also be favourable to the parasite. In particular, parasites may be able to influence the re-allocation of resources in their own favour. We studied the association between the presence of the acanthocephalan parasite, Pomphorhynchus laevis, and inter-individual variation in the lipid and glycogen content of its crustacean host, Gammarus pulex (Amphipoda). Infected gravid females had significantly lower lipid contents than uninfected females, but there was no difference in the lipid contents of non-gravid females and males that were infected with P. laevis. In c…