title: Relatedness predicts multiple measures of investment in cooperative nest construction in sociable weavers.
abstract: Although communal goods are often critical to society, they are simultaneously susceptible to exploitation and are evolutionarily stable only if mechanisms exist to curtail exploitation. Mechanisms such as punishment and kin selection have been offered as general explanations for how communal resources can be maintained. Evidence for these mechanisms comes largely from humans and social insects, leaving their generality in question. To assess how communal resources are maintained, we observed cooperative nest construction in sociable weavers (Philetairus socius). The communal nest of sociable weavers provides thermal benefits for all individuals but requires continual maintenance. We observed cooperative nest construction and also recorded basic morphological characteristics. We also collected blood samples, performed next-generation sequencing, and isolated 2358 variable single nucleotide polymorphisms (SNPs) to estimate relatedness. We find that relatedness predicts investment in cooperative nest construction, while no other morphological characters significantly explain cooperative output. We argue that indirect benefits are a critical fitness component for maintaining the cooperative behavior that maintains the communal good.
authors.affiliation: Department of Ecology & Evolutionary Biology, University of Arizona, Tucson, AZ, USA.
authors.forename: Gavin M
authors.initials: GM
authors.lastname: Leighton
authors.affiliation: Department of Ecology and Evolution, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Echeverri
authors.affiliation: SAFRING: Namibian Ringing Unit, Windhoek, Namibia.
authors.forename: Dirk
authors.initials: D
authors.lastname: Heinrich
authors.affiliation: SAFRING: Namibian Ringing Unit, Windhoek, Namibia.
authors.forename: Holger
authors.initials: H
authors.lastname: Kolberg
keywords: Cooperation; Inclusive fitness; Kin selection; Sociable weavers; Tragedy of the commons