Sexual competition during colony reproduction in army ants

We review the unusual processes of sexual reproduction and colony fission in army ants and briefly compare this to reproduction in other ants. Army ants are a polyphyletic group and are characterized by a syndrome of convergently evolved traits including large colony size, group foraging for large prey, nomadism, cyclical brood production and queens who are large and wingless. Because queens are flightless and never leave their colony, workers are in a position to choose which queen will take over each new colony. Males fly between colonies and must run the gauntlet of the workers in alien ones before they can approach the queen. For this reason, workers can also choose which males will inseminate their queen. Army ant workers may therefore be involved in choosing both the matriarch and patriarch of new colonies. We suggest that this unusual form of sexual selection has led to the close resemblance of conspecific males and females in all the separate lineages of army ants. Males are queen‐like in that they are large and robust, have long cylindrical abdomens, with exocrine glands of similar form and location to those of females and shed their wings when they enter new colonies. Furthermore, when males enter new colonies they are followed by an entourage of workers which resemble those that accompany queens. We suggest that males resemble queens not as a form of deceitful mimicry but because under the influence of sexual selection they have come to use the same channels of communication to demonstrate their potential fitness to the workforce as those used by queens.