Female kin as allies and adversaries under social competition

Animals living in groups must compete for limited resources but can also be highly cooperative in their interactions. Explaining the balance between competition and cooperation is crucial to understanding social behaviour in diverse species from microbes to humans. Although theory of very broad significance provides testable predictions to explain variation in cooperative and competitive behaviours, experimental studies addressing these are currently lacking for vertebrates with typically flexible social behaviour. This project will provide novel experimental tests to determine how the social environment affects cooperative and competitive behaviour in wild house mice.

Relatedness between interacting individuals is thought to be a key predictor of cooperative and competitive behaviour. If competing individuals are able to recognise their relatives, interactions with kin should be more cooperative because by helping a close relative to reproduce, an individual is still passing on some genes to the next generation indirectly. Importantly though, where competition for limited resources is intense between kin, this may reduce or even negate the benefits of cooperating. These underlying principles for understanding patterns of behaviour are particularly relevant to social vertebrates such as mammals, where related members of one sex typically stay in the social group where they were born rather than disperse. However these key general principles have proved difficult to test experimentally, in part due to limited information regarding kin recognition ability of focal species. Our latest research has identified mechanisms used by female house mice to recognise their relatives. Building on this important advance, we now propose to test for predicted responses to reproductive competition within and between female kin groups.

We will manipulate the complex social environment of wild house mice under carefully controlled naturalistic conditions. Our experiments are designed to disentangle effects of competition both within and between kin groups and social groups, and will allow us to assess how responses to social competition are mediated under different conditions. We will quantify and compare the affiliative, cooperative and aggressive behaviour of female mice under contrasting conditions of relatedness of competitors and intensity of competition. Oxytocin (OT) is a peptide hormone and neurotransmitter that is currently receiving very wide attention for its important role in the regulation of social behaviour. We will test for influences of social competition on female OT profiles linked to behaviour, and for evidence that OT facilitates intergenerational transmission of cooperative behaviour among kin via communal rearing of young. We will also quantify variation in female reproductive success under contrasting levels of social competition, and test if reproductive suppression of young females in response to a known chemical cue is dependent on relatedness of competitors in their social environment.

Understanding the conditions and mechanisms that promote social tolerance, aggression and reproductive suppression in mammals has very broad potential applications. As well as beneficiaries in diverse academic fields (evolutionary biology, behavioural ecology, population biology, psychology, anthropology, neurobiology), the work has important potential economical and societal applications. Understanding the factors that promote social tolerance or trigger aggression is of particular significance for users who manage animals, whether wild, laboratory or livestock. These include those managing or breeding endangered animals for conservation purposes, using animals in research, and in the farming industry. The study of olfactory cues used in reproductive suppression of wild house mice is also of direct relevance to long-term development of new methods of rodent pest control, of fundamental significance to global food security.

The proposed research has fundamental implications for understanding variation in the social behaviour of vertebrate animals. This offers broad potential economical and societal impacts over both short and long-term timescales. Understanding the factors that promote social tolerance or trigger aggression is of particular significance for users who manage animals, whether wild, laboratory or livestock - for example those managing or breeding endangered animals for conservation purposes (conservationists, zoological curators), using animals in research and testing (animal care staff, researchers), and associated regulators and animal welfare advisors (Home office inspectorate, NC3Rs, RSPCA, UFAW), and those involved with the farming industry (farmers, veterinary surgeons, animal breeding industry). Understanding social, environmental and developmental influences on aggression and the maintenance of social tolerance has broad relevance for: i) captive management and breeding of wild animals for conservation; ii) welfare of laboratory animals; iii) better understanding of unexplained variation among laboratory mice (e.g. in biomedical research) where the influences of social grouping on females are largely unknown; iv) management and breeding of livestock where there are problems in maintaining high reproductive performance and welfare; v) animal models of social cognition and behaviour used in biomedical research. In addition the study of olfactory cues used in reproductive suppression of wild house mice is of direct relevance to long-term development of new methods of pest control, of fundamental significance to global food security and to reducing rodent-borne zoonoses.

Quality of life will be enhanced by knowledge resulting from this research through education and increased public understanding of science. The subject area of the proposed research is likely to be of interest to school children studying fundamental aspects of animal behaviour. These users will benefit from a better understanding of both ultimate and proximate mediators of cooperative behaviour. More generally, the public benefit from interest in animal behaviour and evolution, as reflected by the popularity of media articles, TV documentaries and science journalism in these areas. Media interest in the findings of this project will thus enhance public understanding of broader issues relating to science and conservation issues.

The project will also provide career development for the PDRA, with training in transferable skills of communication and multidisciplinary research.