During the hundred-million-year history of ants, polygyny (the formation of multiple queens in a nest) has occurred repeatedly. It is a common feature in some species, but has also been reported in other species. Polygyny can arise through pleometrosis (the fusion of two or more founding queens into a single nest) or reproductive castration (physical elimination of male reproductives).
Polygyny is a type of obligate mutualism, in which two organisms interact to increase their productivity. It has been found in the fire ant (Pheidole californicus), Lasius neglectus, and Lasius flavus. These polygyne ants live in large colonies, with one or more queens per nest.
The number of queens per colony is related to the stages of the colony’s life cycle. During the initial stages of the colony’s life cycle, the number of queens is usually lower than during later stages. In the case of the fire ant, the number of queens per nest can range from one to 40 million.
In some species, the number of queens per nest is higher, which may lead to multiple nesting sites. Typically, multiple queen colonies have more mounds per acre than single-queen colonies. This increase in numbers also increases the number of workers.
Polygyny has several advantages, but there are several disadvantages as well. In some species, workers may have a negative reaction to multiple queens. They may become territorial or lose interest in working for the colony. These disadvantages may arise because polygyny is a result of evolutionary selection.