title: Kin selection and polygyny: can relatedness lower the polygyny threshold?
abstract: Resource polygyny incurs costs of having to share breeding resources for female breeders. When breeding with a relative, however, such costs may be lessened by indirect fitness benefits through kin selection, while benefits from mutualistic behaviour, such as communal defence, may increase. If so, females should be less resistant to sharing a territory with a related female than with a non-related one. We investigated whether kin selection may lower the threshold of breeding polygynously, predicting a closer relatedness between polygynous females breeding on the same territory than between females breeding on different territories. Northern lapwings, Vanellus vanellus, are suitable for testing this hypothesis as they are commonly polygynous, both sexes take part in nest defence, and the efficiency of nest defence increases with the number of defenders. Using an index of relatedness derived from DNA fingerprinting, we found that female lapwings that shared polygynous dyads were on average twice as closely related as were random females. Furthermore, relatedness did not correlate with distance between breeders, indicating that our findings cannot be explained by natal philopatry alone. Our results suggest that the polygyny threshold in lapwings may be lowered by inclusive fitness advantages of kin selection.
authors.affiliation: University Museum of Bergen , University of Bergen , Allégaten 41, 5007 Bergen, Norway.
authors.forename: Gaute
authors.initials: G
authors.lastname: Grønstøl
authors.affiliation: Department of Biological and Environmental Sciences , University of Gothenburg , PO Box 463, 40530 Gothenburg, Sweden.
authors.forename: Donald
authors.initials: D
authors.lastname: Blomqvist
authors.affiliation: Department of Biological and Environmental Sciences , University of Gothenburg , PO Box 463, 40530 Gothenburg, Sweden.
authors.forename: Angela
authors.initials: A
authors.lastname: Pauliny
authors.affiliation: Konrad Lorenz Institute of Ethology, Department of Integrative Biology and Evolution , University of Veterinary Medicine Vienna , Savoyenstrasse 1a, 1160 Vienna, Austria.
authors.forename: Richard H
authors.initials: RH
authors.lastname: Wagner
keywords: kin selection; lapwings; mate choice; polygyny; relatedness