Dominance and policing in social insects: testing the hypotheses in bumblebees

Livesey, Jennifer (2023) Dominance and policing in social insects: testing the hypotheses in bumblebees. Doctoral thesis, University of East Anglia.

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Animal societies can display remarkable levels of cooperation and altruism, but they are still susceptible to conflict and social cheats. Consequently, the maintenance of these societies, over evolutionary time, relies on the evolution of mechanisms that limit exploitation from both external and internal elements. Despite extensive research on conflict and conflict resolution in animal societies, uncertainties remain regarding the role coercive mechanisms, such as dominance and policing, play in enforcing cooperation and preventing group exploitation. Through a series of quantitative experiments involving colonies of the Buff-tailed bumblebee Bombus terrestris, I investigate uncertainties surrounding (1) the exact origins of worker policing (egg-eating) in eusocial societies, (2) the ultimate function of dominance behaviours in animal societies, and (3) the underlying factors behind variations in intrinsic quality, reproductive success, and longevity in workers of eusocial Hymenoptera. In an experiment aimed at discerning the origin of non-reproductive worker policing in eusocial Hymenoptera, partial support was found for both the public goods hypothesis and the selfish policing hypothesis, leaving the origin of non-reproductive worker policing unclear. However, additional findings of an association among reproductive workers between egg-laying, egg-eating and aggression provide new support for policing by reproductive workers originating as selfish policing. Behavioural analyses of queenless groups of full-sister B. terrestris workers also revealed that while (dominant) alpha workers were unable to completely suppress egg-laying in betas or subordinates, they effectively monopolised reproduction by exhibiting significantly higher rates of aggression, policing, and egg survivorship than other group members. These findings strongly support the hypothesis that dominance is positively correlated with reproductive success in B. terrestris workers and that increasing direct fitness is the ultimate function of dominance behaviour. Finally, an experiment that aimed to determine if the quantity of nutrition provided during larval development influences a worker's size and intrinsic quality did not generate distinct worker body sizes as intended. Nonetheless, associations between reproductive behaviours and longevity were still evident, as reproductive workers exhibited greater body size and longevity compared to non-reproductive workers. The data also revealed significant associations among workers between egg-laying, egg-eating, aggression, and body size, supporting the hypothesis that variations in intrinsic worker quality, reflected in body size, underlie positive associations between fecundity and longevity in B. terrestris workers. Overall, the findings of this thesis provide valuable insights into the complex dynamics of cooperation and conflict in animal societies, particularly in colonies of bumblebees and comparable social systems.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Zoe White
Date Deposited: 27 Jun 2024 14:44
Last Modified: 27 Jun 2024 14:44


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