Ant colonies are intricate societies where each member plays a specific role, with the queen ant at the center of reproduction and colony maintenance. The number of queens in an ant colony is not fixed, varying significantly across thousands of ant species. This variation influences colony size and survival strategies. The queen’s ability to lay eggs is fundamental for colony growth and continuation.
The Monogynous Colony: One Sovereign Ruler
Many ant species operate under a monogynous system, meaning each colony is governed by a single queen. The queen is typically the sole reproductive female, responsible for laying all eggs that develop into workers, soldiers, and future reproductive ants. A prime example is the black garden ant, Lasius niger, where colonies commonly contain one queen. Early in colony founding, Lasius niger queens may initially tolerate two to three others, but they often fight until only one remains once the first workers emerge.
This single-queen structure offers distinct advantages, including clear leadership and efficient resource allocation. With one queen, there is centralized control over reproduction, which can lead to a more cohesive colony. The absence of multiple egg-layers can reduce internal conflict, as all efforts are directed towards supporting a single reproductive individual. The colony’s fate is closely linked to the survival of its single queen; if she dies, the colony’s ability to reproduce typically ends, leading to its decline.
The Polygynous Colony: A Shared Monarchy
In contrast, polygynous colonies feature multiple queens coexisting and reproducing within the same nest. This social structure is observed in various species, including the invasive red imported fire ant (Solenopsis invicta) and some Formica species. These queens share the egg-laying duties, contributing to the colony’s overall reproductive output.
The coexistence of multiple queens is managed through various mechanisms. In some cases, queens may establish a colony together from the outset (pleometrosis). More commonly, new queens are accepted into existing colonies (secondary polygyny). This shared reproductive effort provides significant benefits, such as increased resilience against queen mortality; if one queen dies, others can continue reproduction. Polygyny also often leads to faster colony growth and a greater reproductive output due to the combined egg-laying capacity of several queens.
Life and Longevity: How Queen Number Shapes the Colony
The number of queens profoundly impacts a colony’s overall life, dynamics, and survival strategies. Monogynous colonies, with their single queen, tend to have a more concentrated genetic relatedness among workers, which can foster strong cooperation. However, their reliance on one queen makes them vulnerable; her death can lead to the colony’s demise, as she is the sole source of new offspring. Some monogynous queens, like Lasius niger, can live for an exceptionally long time, up to 29 years, which helps compensate for the single point of failure in reproduction.
Polygynous colonies, conversely, gain resilience and faster growth from their multiple queens. This shared reproductive capacity allows for increased worker production and can lead to significantly larger colony sizes, with some supercolonies housing millions of queens. This structure also enables colony expansion through budding, where a subset of queens and workers splits off to form a new colony. Polygyny is particularly advantageous in unstable environments or for invasive species, as it allows for rapid exploitation of new habitats and a higher probability of reproductive success if parts of the colony become isolated. The trade-off in polygynous colonies can be reduced genetic relatedness among workers, which may sometimes affect cooperation levels, although the sheer scale of resources often mitigates this.