Affiliation:
1. School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia
2. Department of Biological Sciences, Macquarie University, New South Wales, Australia
Abstract
Evolutionary arms races can alter both parasite infectivity and host resistance, and it is difficult to separate the effects of these twin determinants of infection outcomes. We used a co-introduced, invasive host–parasite system (the lungworm
Rhabdias pseudosphaerocephala
and cane toads
Rhinella marina
), where rapid adaptation and dispersal have led to population differences in infection resistance. We quantified behavioural responses of parasite larvae to skin-chemical cues of toads from different invasive populations, and rates at which juvenile hosts became infected following standardized exposure to lungworms. Chemical cues from toad skin altered host-seeking behaviour by parasites, similarly among populations. The number of infection attempts (parasite larvae entering the host's body) also did not differ between populations, but rates of successful infection (establishment of adult worm in host lungs) were higher for range-edge toads than for range-core conspecifics. Thus, lower resistance to parasite infection in range-edge juvenile toads appears to be due to less effective immune defences of the host rather than differential behavioural responses of the parasite. In this ongoing host–parasite arms race, changing outcomes appear to be driven by shifts in host immunocompetence.
Funder
Australian Research Council
Subject
General Agricultural and Biological Sciences,Agricultural and Biological Sciences (miscellaneous)
Cited by
2 articles.
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