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Co-invaders: The effects of alien parasites on native hosts

Lymbery, A.J.ORCID: 0000-0002-0542-3446, Morine, M., Kanani, H.G., Beatty, S.J.ORCID: 0000-0003-2620-2826 and Morgan, D.L. (2014) Co-invaders: The effects of alien parasites on native hosts. International Journal for Parasitology: Parasites and Wildlife, 3 (2). pp. 171-177.

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We define co-introduced parasites as those which have been transported with an alien host to a new locality, outside of their natural range, and co-invading parasites as those which have been co-introduced and then spread to new, native hosts. Of 98 published studies of co-introductions, over 50% of hosts were freshwater fishes and 49% of parasites were helminths. Although we would expect parasites with simple, direct life cycles to be much more likely to be introduced and establish in a new locality, a substantial proportion (36%) of co-introductions were of parasites with an indirect life cycle. Seventy-eight per cent of co-introduced parasites were found in native host species and can therefore be classed as co-invaders. Host switching was equally common among parasites with direct and indirect life cycles. The magnitude of the threat posed to native species by co-invaders will depend, among other things, on parasite virulence. In 16 cases where co-introduced parasites have switched to native hosts and information was available on relative virulence, 14 (85%) were more virulent in native hosts than in the co-introduced alien host. We argue that this does not necessarily support the naïve host theory that co-invading parasites will have greater pathogenic effects in native hosts with which they have no coevolutionary history, but may instead be a consequence of the greater likelihood for parasites with lower virulence in their natural host to be co-introduced.

Item Type: Journal Article
Murdoch Affiliation(s): Freshwater Fish Group & Fish Health Unit
School of Veterinary and Life Sciences
Publisher: Elsevier Limited
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