title: Cooperative investment in public goods is kin directed in communal nests of social birds.
abstract: The tragedy of the commons predicts social collapse when public goods are jointly exploited by individuals attempting to maximize their fitness at the expense of other social group members. However, animal societies have evolved many times despite this vulnerability to exploitation by selfish individuals. Kin selection offers a solution to this social dilemma, but in large social groups mean relatedness is often low. Sociable weavers (Philetairus socius) live in large colonies that share the benefits of a massive communal nest, which requires individual investment for construction and maintenance. Here, we show that despite low mean kinship within colonies, relatives are spatially and socially clustered and that nest-building males have higher local relatedness to other colony members than do non-building males. Alternative hypotheses received little support, so we conclude that the benefits of the public good are shared with kin and that cooperative investment is, despite the large size and low relatedness of these communities, kin directed.
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK.
authors.forename: René E
authors.initials: RE
authors.lastname: van Dijk
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Kaden
authors.forename: Araceli
authors.initials: A
authors.lastname: Argüelles-Ticó
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Dawson
authors.forename: Terry
authors.initials: T
authors.lastname: Burke
authors.forename: Ben J
authors.initials: BJ
authors.lastname: Hatchwell
mesh_terms: D000818:Animals; D003299:Cooperative Behavior; D005260:Female; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D012919:Social Behavior; D046370:Sparrows / Q000235:genetics / Q000502:physiology*
keywords: cooperation; kin selection; public goods; social network theory; tragedy of the commons