Research on cooperatively breeding species has shown that their population dynamics can differ from those of conventional breeders. Populations of obligate cooperators are structured into social groups, the link between individual behaviour and population dynamics is mediated by group-level demography, and population dynamics can be strongly affected both by features of sociality per se and by resultant population structure. Notably, groups may be subject to inverse density dependence (Allee effects) that result from a dependence on conspecific helpers, but evidence for population-wide Allee effects is rare. To develop a mechanistic understanding of population dynamics in highly social species, we need to investigate how processes within groups, processes linking groups, and external drivers act and interact in space and time to produce observed patterns.

Here, I consider these issues as they relate to meerkats, Suricata suricatta, obligate cooperative breeders that inhabit southern Africa. I use mathematical and statistical models, in conjunction with long-term data from a wild meerkat population, to explore population dynamics, group dynamics, group demography, Allee effects, and territory dynamics in this species. I start out by examining broad-scale patterns, and then examine some of the constituent processes.

In Chapter Two, I assess the ability of phenomenological models, lacking explicit group structure, to describe population dynamics in meerkats, and I assess potential population-level Allee effects. I detect no Allee effect and conclude that explicit consideration of population structure will be key to understanding the mechanisms behind population dynamics in cooperatively breeding species.

In Chapter Three, I focus on annual group-level dynamics. Using phenomenological population models, modified to incorporate environmental conditions and potential Allee effects, I first investigate overall patterns of group dynamics and find support for only conventional density dependence that increases after years of low rainfall. To explain the patterns, I examine demographic rates and assess their contributions to overall group dynamics. While per-capita meerkat mortality is subject to an Allee effect, it contributes relatively little to observed variation, and other (conventionally density dependent) demographic rates – especially emigration – govern group dynamics.

In Chapter Four, I investigate group dynamics in more detail. I model demographic rates in different sex, age, and dominance classes on short timescales. Using these to build predictive and individual-based simulation models of group dynamics, I examine the demographic mechanisms responsible for declines in group size after dry years. Results reveal the delayed effect of environmental conditions, partially mediated by group structure.

In Chapter Five, I explore meerkat territorial patterns. Using mechanistic home-range models, I examine group interactions, habitat selection, territory formation, and territory movement. I use meerkat data to test proposed improvements to these models, and I use the model results to start building a picture of spatial processes in meerkat population dynamics, laying the groundwork for future research. This thesis highlights the role of environment and social structure in characterizing population dynamics. I discuss the implications of my findings for the population dynamics of cooperative breeders and for population dynamics generally, noting the importance of sub-populations in drawing conclusions about socially complex systems.