TITLE: Kleptoparasitic melees  - using game theory to model food stealing featuring contests with multiple individuals
SPEAKER: Professor Mark Broom (School of Engineering and Mathematical Sciences, City University, London)

ABSTRACT:

We start by introducing the basic ideas of evolutionary game theory including pure and mixed strategies, payoffs and evolutionarily stable strategies. This includes a brief look at some classical examples, including the Hawk-Dove game and the sex ratio game. We then consider a model of kleptoparasitism, the stealing of food from one animal by another. We investigate a model where individuals are allowed to fight in groups of more than two, as often occurs in real populations, but which has not featured in previous theoretical models. We find the equilibrium distribution of the population amongst various behavioural states, conditional upon the strategies played and environmental parameters, and then find evolutionarily stable strategies (ESSs) for the challenging behaviour of the participants. We show that ESSs can only come from a restricted subset of the possible strategies and that there is always at least one ESS. We show that there can be multiple ESSs, and indeed that the number of ESSs is unbounded. Finally we discuss the biological circumstances when particular ESSs occur in terms of key parameters such as the availability of food and the cost of fighting.