Cooperation- Assessing the role of direct benefits in the evolution of cooperation

Cooperation is present at all levels of biological organisation, from bacteria to vertebrates such as humans. The evolution of cooperation has been largely explained by kin selection theory and thus by indirect fitness benefits obtained by individuals who help relatives. One of the main challenges currently is to empirically test the potential additional role of the direct benefits obtained by helpers and especially of those obtained through social and sexual selection. Social and sexual selection predict that more cooperative individuals are preferentially chosen as social or sexual partners, but these hypotheses are contentious because it remains debated whether cooperation can be reliable, i.e. linked to individual quality or future cooperativeness. If information is not reliable, cooperation cannot be used in partner choice.To determine whether sexual or social selection play a role in the evolution of cooperation, we have 3 objectives.

(1) To test overlooked mechanisms that can ensure the reliability of cooperation and thus its association with condition and/or future cooperativeness.

(2) To measure the social and sexual benefits of cooperation for the cooperators and the individuals that associate with them.

(3) To test the links between cooperation and dominance to examine one of the expected consequences of the occurrence of direct benefits for helpers, which is that they lead to competition to cooperate. We propose to work on a colonial cooperative breeding bird, the sociable weaver. These weavers cooperate around multiple tasks, most notably to breed, to build a massive communal nest (wherein up to 200 birds can roost and breed), and to collectively defend nests against predators.