Alien eggs in duck nests: brood parasitism or a help from Grandma?
Article first published online: 20 JUN 2011
© 2011 Blackwell Publishing Ltd
Volume 20, Issue 15, pages 3237–3250, August 2011
How to Cite
TIEDEMANN, R., PAULUS, K. B., HAVENSTEIN, K., THORSTENSEN, S., PETERSEN, A., LYNGS, P. and MILINKOVITCH, M. C. (2011), Alien eggs in duck nests: brood parasitism or a help from Grandma?. Molecular Ecology, 20: 3237–3250. doi: 10.1111/j.1365-294X.2011.05158.x
- Issue published online: 21 JUL 2011
- Article first published online: 20 JUN 2011
- Received 1 March 2011; revision received 29 April 2011; accepted 5 May 2011
- eider duck;
- indirect fitness;
- intraspecific brood parasitism;
- Somateria mollissima
Intraspecific brood parasitism (IBP) is a remarkable phenomenon by which parasitic females can increase their reproductive output by laying eggs in conspecific females’ nests in addition to incubating eggs in their own nest. Kin selection could explain the tolerance, or even the selective advantage, of IBP, but different models of IBP based on game theory yield contradicting predictions. Our analyses of seven polymorphic autosomal microsatellites in two eider duck colonies indicate that relatedness between host and parasitizing females is significantly higher than the background relatedness within the colony. This result is unlikely to be a by-product of relatives nesting in close vicinity, as nest distance and genetic identity are not correlated. For eider females that had been ring-marked during the decades prior to our study, our analyses indicate that (i) the average age of parasitized females is higher than the age of nonparasitized females, (ii) the percentage of nests with alien eggs increases with the age of nesting females, (iii) the level of IBP increases with the host females’ age, and (iv) the number of own eggs in the nest of parasitized females significantly decreases with age. IBP may allow those older females unable to produce as many eggs as they can incubate to gain indirect fitness without impairing their direct fitness: genetically related females specialize in their energy allocation, with young females producing more eggs than they can incubate and entrusting these to their older relatives. Intraspecific brood parasitism in ducks may constitute cooperation among generations of closely related females.