Abstract

Cooperation is a social interaction that occurs at all biological levels; as such it is a major force underlying biological organization. Cooperative breeding occurs when individuals help to raise offspring that are not their own. Cooperative breeding is widespread, however, it is a conundrum: Why do individuals postpone their own breeding to help others to breed, rather than breeding themselves? This is puzzling because natural selection is a competitive process that favours genes that are maximised in future generations. Social evolution theory resolves this puzzle: Individuals can spread their genes, not only by breeding themselves, but also by helping their relatives to breed, as relatives share genes. Although social evolution theory has been hotly debated, it is well established. My work aims to test social evolution theory using long-term datasets from wild populations that differ in their extent of cooperative breeding. Even with such rare long-term data, testing social evolution theory in wild populations is complex, as the parameters required to do this are not easily measured. To understand why individuals breed cooperatively it is necessary to quantify the costs and benefits of cooperative breeding, along with the relatedness of interacting individuals, which is not a trivial matter. I will present an overview of how the mating system impacts on relatedness, whether relatedness promotes cooperation, and whether there are fitness benefits to cooperative breeding, using data from European badgers and Seychelles warblers.