Behaviour 2019
The evolution of a pheromone: From individual recognition to chemical signaling in ants
Juergen Liebig, Kevin Berthelot. Arizona State University, Tempe, Arizona, United States

The sender-precursor model of signal evolution states that a signal originates from a cue that informs about a sender’s condition. This also applies to the evolution of pheromones. We demonstrate in one ant species how queen pheromones might have evolved. In ants, the development of a colony from a founding queen to a large society with thousands of members recapitulates the evolution of ant societies. These societies are defined by reproductive division of labor between the queen and her workers which is regulated by queen pheromones. One of the queen pheromone properties is the induction of queen attraction. In our trials with founding colonies, the cuticular chemical profile of the mother queen was more attractive to workers than that of a foreign founding queen which suggests learned individual queen recognition. In mature colonies, the cuticular profile of a foreign fertile queen was however as attractive as that of the mother queen. This means that a learned cue is replaced by an anonymous queen pheromone in the colony ontogeny. Given that such signaling mechanisms are also present in bee and wasp societies, the latter may have evolved queen chemical signaling similarly.