Individual strategies, group dynamics and population regulation in singular cooperative breeders

Lead Research Organisation: University of Cambridge
Department Name: Zoology

Abstract

Most detailed studies of the regulation of population density in birds and mammals have focussed on studies where recruitment and survival decline as population density increases, eventually limiting population size. However, in some species, recruitment and survival increase with rising density, generating positive correlations known as Allee effects. Empirical studies show that effects of this kind are more widespread than was previously thought though our understanding of their causes and ecological consequences is still very limited. These effects appear to be particularly pronounced in cooperative breeders where one female in each group monopolises reproduction and non-breeding adults assist her to raise her offspring but, although studies have commonly investigated the evolution of reproductive strategies in these species, the ecological mechanisms controlling group size and population density have rarely been explored. This study will investigate the ecological processes limiting group size and population density in singular cooperative breeders using wild Kalahari meerkats (Suricata suricatta) as a model. It will test the prediction that positive correlations between group size and breeding success are a consequence of increases in the ability of group members to detect predators and will determine whether group size is limited by increasing rates of dispersal by subordinate females, caused by increasing intolerance by dominant females living in large groups. It will explore the effects of regulatory processes at the group level on dynamics and demography at the population level. Finally, it will investigate how group size and population dynamics are affected by variation in rainfall, food availability and disease. By exploring the unusual ecological mechanisms affecting population dynamics in meerkats, the project will provide an informed basis for the management and conservation of other animals subject to strong Allee effects.

Publications

10 25 50
 
Description (1) We have tested the prediction that recruitment to the population rises with population density in cooperative breeders and shown that this is not the case.
(2) We have modelled changes in population density and demography and measured the relative importance of variation in rainfall, temperature and population density.
(3) We have documented the growth of large samples of animals from birth to death and assessed the effects on this of rainfall, group size, birth weight and maternal status.
(4) We have confirmed that females that acquire dominant positions subsequently show a period of accelerated growth and shown that the magnitude of this is inversely related to the difference in weight between them and their closest competitor of the same sex.
(5) We have used experiments involving the manipulation of growth to show that subordinate animals increase their growth rate if the closest competitor of the same sex approaches them in weight.
Exploitation Route Our demographic results are relevant to the management and conservation of cooperative breeders. Our evidence of competitive growth is of potential relevance both to animal breeders and to medical practice.
Sectors Communities and Social Services/Policy,Education,Environment,Culture, Heritage, Museums and Collections

 
Description Our research on meerkats is widely referenced in research on organismal biology, generating a personal H score of 80. The films about our work have attracted substantial attention and provided the general public with insight into the structure and function of animal societies. Our work has also formed the basis for collaborative research with members of staff at Duke, Gottingen, Zurich and Pretoria, and has helped to generate two major grants: one at Duke to investigate the effects of maternal testosterone levels on offspring development; one from the ERC to me to explore developmental aspects of variation in cooperative behaviour, worth around 2.5 million euros.
First Year Of Impact 2012
Sector Environment
Impact Types Cultural

 
Description Seventh Framework Programme-Advanced Grant-European Research Council
Amount € 2,499,532 (EUR)
Funding ID ERC-2011-AdG-294494 
Organisation European Research Council (ERC) 
Sector Public
Country European Union (EU)
Start 07/2012 
End 06/2017
 
Description Collaborator: Professor Christine Drea 
Organisation Duke University
Department Evolutionary Anthropology
Country United States 
Sector Academic/University 
PI Contribution We have assisted Professor Drea in investigating the organisational effects of maternal testosterone in meerkats.
Collaborator Contribution Professor Drea has employed an assistant who has worked with us in the Kalahari, extending the number of groups we have been able to sample.
Impact MULTI-DISCIPLINARY: Behaviour; Endocrinology.
Start Year 2011
 
Description Collaborator: Professor Marta Manser 
Organisation University of Zurich
Department Institute of Evolutionary Biology and Environmental Studies
Country Switzerland 
Sector Academic/University 
PI Contribution We have provided Professor Manser's team with access to habituated animals and to long-term, individual-based data.
Collaborator Contribution Professor Manser's team has explored the communication system of meerkats, extending the range of research that we are involved in.
Impact MULTI-DISCIPLINARY: Endocrinology; Behaviour. Santema, P., Teitel, Z., Manser, M., Bennett, N. and Clutton-Brock, T. (2013) Effects of cortisol administration on cooperative behavior in meerkats. Behavioral Ecology. doi: 10.1093/beheco/art039. Zöttl, M., Lienert, R., Clutton-Brock, T., Millesi, E. and Manser, M. B. (2013) The effects of recruitment to direct predator cues on predator responses in meerkats. Behavioral Ecology 24: 198-204.
Start Year 2011
 
Description Documentary films 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Two documentaries on our work by Discovery and National Geographic

Regular interest in animal societies and meerkats in particular by other scientists/television researchers/general public.
Year(s) Of Engagement Activity 2012,2013