We have examined the genetic diversity using mitochondrial COI and ND2 sequence data from 306 specimens of the amphi-Atlantic-distributed amphipod Gammarus duebeni. Marine populations from the Atlantic Ocean, the Baltic and North Sea, as well as freshwater populations from Ireland, Cornwall and Brittany were analysed. G. duebeni is a complex of five allopatric lineages. Freshwater populations r...

Many parasites with complex life cycles increase the chances of reaching a final host by adapting strategies to manipulate their intermediate host's appearance, condition or behaviour. The acanthocephalan parasite Pomphorhynchus laevis uses freshwater amphipods as intermediate hosts before reaching sexual maturity in predatory fish. We performed a series of choice experiments with infected and ...

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 var...

Manipulative endoparasites can alter the behaviour and the physiology of their intermediate hosts in ways that increase the probability of successful transmission to the final host. This requires that the parasite is able to circumvent its host's immune defence. Successful immune evasion may depend on host-parasite coevolutionary history and the appearance of new hosts invading the local host p...