Cooperation ties animals together into social groups that often demonstrate complex emergent behaviours. One striking example of this are social insect societies that emerge from extreme cooperative behaviour and have an important impact in many ecosystems. Colonies of most social insects construct and inhabit a single nest. However, colonies of some species have been found to spread across many different nests โ known as polydomy. This strategy is thought to have evolved in response to several different drivers, such as increased foraging efficiency, avoiding nest-size limitations and territory defence. In this thesis, I present studies that investigated how polydomous colonies function and the reasons that some, but not all, ant species use polydomy as a strategy. I used a mathematical model to demonstrate that decentralization of the nest population can be advantageous under a variety of different conditions, which explains why polydomous species are so behaviourally and phylogenetically diverse. Using a longitudinal study of several years of data on a set of polydomous colonies I found that resource sharing networks become more static over a season and that while nest foundation occurs throughout the season, nest abandonment occurs at a much faster rate in the latter part of the season. Through sampling several polydomous colonies, I found that there is a correlation between relatedness of the inhabitants of different nests and the rate of resource sharing between the nests. The most likely mechanism for this is that nests that share resources become more closely related due to migration and brood transfer. Finally, using a resource manipulation study, I found that resource-sharing networks can adapt in response to change in the availability of food. Together these results demonstrate how ant colonies can use polydomy to their advantage and the various factors that are important in determining the dynamics of these complex societies
