Evolutionary theory predicts individuals should behave selfishly, yet cooperation is common throughout the animal kingdom. Perhaps one of the most extreme forms of cooperation is where individuals care for the young of others (‘cooperative breeding’), forgoing their own chances of reproduction. While this behaviour may appear an evolutionary puzzle, it is found in a diverse range of animals, including some of the most successful on the planet (humans, ants and termites). Cooperative breeding systems are excellent models for studying the evolution of cooperation because within each group multiple individuals contribute to the same communal activity, such as feeding and protecting young.
A striking feature of many cooperative societies is the diversity in cooperative tactics among individuals: some spend their entire lives caring for young that are not their own, while others do not help at all. Thus, we can ask what distinguishes those group members that help a lot from those that help very little. Accounting for these patterns of behaviour is a crucial step in understanding the evolution and maintenance of cooperative breeding.
Current questions include: Are individual cooperative strategies in babblers driven predominantly by their associated costs or benefits? Do individual differences in cooperation arise due to variation in direct and/or indirect benefits? What explains the pronounced sex differences in cooperative behaviour?
Coordinating group activities
How do individuals living in groups coordinate their teamwork such that they cooperate with maximum efficiency? When there are conflicts of interest, does coordination break down? I am currently investigating the cues individuals use to adjust their investment in communal activities, how they respond to the investment of other group members and under what circumstances coordination deteriorates.
Current questions include: Do members of the same babbler group use different provisioning rules? Do individuals use cues directly from the chicks, such as begging intensity, or cues from other group members, to adjust their investment? Do individuals respond in the opposite or in the same direction as changes in provisioning they observe in other group members? Is the nature of this response governed by the type of individual observing and/or being observed (breeder vs. helper, old vs. young, male vs. female)? Does group size dictate the efficiency with which these cues are used, and hence breeding success?
Highly cooperative eusocial insects are characterised by division of labour where individuals typically specialise in particular roles within their group. While the degree of specialisation in cooperative vertebrates is less pronounced, there is some evidence for an intermediate division of labour. In chestnut-crowned babblers, for example, breeding females work much less hard than other group members at feeding chicks, potentially because they are solely responsible for the production and incubation of eggs.
Current questions include: Do fecundity and incubation costs drive reduced female investment in chick provisioning, within and among cooperatively breeding birds? Does investment in one cooperative behaviour trade-off against investment in others?
Dr Sinead English, University of Oxford
Dr Simon Griffith, Macquarie University
Dr Lee Ann Rollins, Deakin University
Dr Andy Russell, University of Exeter
James Savage, University of Cambridge