Attention seeking in a spatially explicit game of mate choice and the evolution of dimorphic ornaments

The evolution of conspicuous signals fascinated biologist ever since Darwin. The Handicap Principle was dominant explanation in the last decades; it proposed that exaggerated and conspicuous signals are costly signals of quality. There are other less popular explanations however, one them is that conspicuous signals function to call the attention of potential receivers. These ‘attention seeking displays’ need not reveal the quality of the signaller. There are many empirical examples and recently the idea was modelled in terms of a simple action-response game. However, action-response games model an interaction of a pair of signaller and receiver, thus they omit potential competition between signallers, which could be a crucial force behind the evolution of attention-seeking displays. Here I model this competition in a spatially explicit model of mate choice where males can give a continuous signal to call the attention of potential mates. The results show that attention-seeking displays readily evolve to the allowed maximum when the cost of signalling is low. However, dimorphism evolves when the cost of signalling is high. The population consist of two types of males at this dimorphic state: males that do not give a signals and males that give the highest intensity signal possible. The results show that variation in quality is not a necessary requirement for the evolution of dimorphic traits.