Parasite-induced surfacing in the cockle Austrovenus stuchburyi: adaptation or not?
Article first published online: 29 JAN 2004
Journal of Evolutionary Biology
Volume 17, Issue 2, pages 247–256, March 2004
How to Cite
Tompkins, D. M., Mouritsen, K. N. and Poulin, R. (2004), Parasite-induced surfacing in the cockle Austrovenus stuchburyi: adaptation or not?. Journal of Evolutionary Biology, 17: 247–256. doi: 10.1111/j.1420-9101.2003.00688.x
- Issue published online: 29 JAN 2004
- Article first published online: 29 JAN 2004
- Received 7 October 2003; revised 21 November 2003; accepted 23 November 2003
- complex life cycle;
- Curtuteria australis;
- extended phenotype;
- parasite manipulation;
- simulation model;
Parasite manipulation of host behaviour is a compelling example of the extended phenotype. However, in many cases, such manipulation may be incorrectly assumed. Previous work has demonstrated that Austrovenus stuchburyi cockles stranded on mud-flat surfaces due to an inability to re-burrow both contain significantly more metacercariae of the trematode Curtuteria australis and are predated by the definitive host of this parasite at a faster rate than burrowed cockles. These results have been interpreted as strong evidence for a manipulation of cockle behaviour by the trematode to facilitate transmission to the definitive host. The model presented here, however, indicates that the selective advantage to the parasite of the altered host behaviour is currently of a negligible level at our study site that is highly unlikely to have been realized as an adaptation over evolutionary time. Hence, there are no grounds on which the more parsimonious explanation, that the altered host behaviour observed is simply an incidental side-effect of infection, can be rejected. We thus maintain that for any change in the behaviour of infected hosts to be confirmed as potentially a parasite trait that has evolved in response to selection, the adaptive benefit taking into account the entire parasite life cycle may need to be considered.