Alien eggs in duck nests: brood parasitism or a help from Grandma?

• Main Authors: Ralph Tiedemann, Kirsten B. Paulus, Katja Havenstein, Aevar Petersen, Peter Lyngs, Michel C. Milinkovitch
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: eider duck; indirect fitness; intraspecific brood parasitism; microsatellites; relatedness; Somateria mollissima Received; Somateria mollissima
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.470.7820; http://www.lanevol.org/reprints/Tiedemann_etal_MolEcol_2011.pdf

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