How ants mate? — Bailey’s student essay
How Ants Mate?
The long established and widely accepted model regarding ant reproduction is that in which one or many mated queens carry the responsibility of producing offspring. In this model, the ability of the queen to produce offspring is the determining factor for the success of the colony on a local level, and on a macroscopic scale for the success of ants as a whole.
The problem with this model is that it fails to account for the widespread deviations that are observable within the ant population at large. Ants are an incredibly adaptable species, with alternative reproduction strategies to help account for populations without queens present. This adaptability has led to the success of ants as a globally occurring species, and contributes to their ability to persist in areas actively hostile to their species (e.g. places of residence).
The first meaningful distinction between ant colonies and their respective reproductive strategies is the difference between monogynous (roughly, single-queen) and polygynous (roughly, multiple-queen) hierarchies. The key difference between these two strategies is succinctly outlined in “Ant Reproductive Strategies”:
Monogyny is typically associated with mating on the wing, dispersal, and indepen- dent colony founding, whereas in polygynous species queens mate within the nest or in its immediate neighborhood and new colonies are founded by the fragmentation of large colonies, i.e., “budding”. — Heinze, Tsuji 1995
Queens from monogynous colonies tend to be heavier, bigger, and featuring larger fat reserves than those from polygynous colonies, which better equip them for the harsh realities of not only founding a new, independent colony, but also for the initial foraging efforts that supply the nascent colony with the food it needs to grow and mature (Heinze, Tsuji 1995). Polygynous colonies instead focus on allowing multiple queens to rapidly expand its population, which divides itself into smaller colonies as necessary.
While monogynous colonies appear to be the default state for an ant colony, and especially so in colonies that rely on winged queens, there is a non-negligible portion of polygynous colonies that seems to equalize to some degree in colonies which rely on wingless females.
The second noteworthy “aberration” in ant colonies is the presence of “gamergates” or thelytokous reproduction. Simply put, a gamergate is a female worker ant who has adapted the ability to reproduce. “Winged queens disperse whereas gamergates found new nests by budding”, which is similar to the style of colonization employed by polygynous populations (Heinze, Tsuji 1995). It is worth noting that the presence of gamergates is quite rare, with the coexistence of a queen even moreso.
A study on gamergates and their effects on populations determined that species with a singular gamergate were unlikely to have queens present, while species with multiple gamergates were more likely to do so (Monnin & Peters, 2007). The paper also found that colonies with gamergates present were “potentially immortal” as they could be easily replaced by any female worker in the event of their death (Monnin & Peeters 2007). While gamergate-only colonies are limited to “budding” in terms of mechanisms of spread, a hybrid gamergate-queen colony could perform both “budding” and the “dispersal” method, in which a queen journeys forth on its own to seed a new colony elsewhere. (Monnin & Peeters 2007).
In the niche example provided by wasmannia auropunctata fire ants, there were several systems of reproduction in place, each of which corresponded to a different “caste” or function within the colony (Foucaud et. al, 2009). In a laboratory, Foucaud et. al were able to isolate, manipulate and study the distinctions within this species’ highly complex system of reproduction and find the following methods: males produced asexually by means of clonality (males with the same genetic makeup as their fathers), queens which are produced by thelytokous parthenogenesis (genetically unique females produced asexually), and workers which were produced sexually (Foucaud et. al, 2009). While this is an incredibly niche scenario that does not apply to ants at large, it is still a testament to the adaptability and complexity of their reproductive methods.
The flexibility of reproduction methods within ant populations can help to account for the apparent speed at which they are able to expand their populations. With so many methods available for the continuation of their colonies, ants are able to withstand and survive hostile environments, and many efforts to remove them from those environments. In some cases, a colony may even be able to survive, stabilize, and regroup from all but the most thorough of population loss.
Author: Bailey Hardt
Arizona State University
Sources
- Heinze, Tsuji 1995
- Foucaud, J, et al. “Thelytokous Parthenogenesis, Male Clonality and Genetic Caste Determination in the Little Fire Ant: New Evidence and Insights from the Lab.” Heredity, vol. 105, no. 2, 2009, pp. 205–212., https://doi.org/10.1038/hdy.2009.169.
- Heinze, Jürgen, and Kazuki Tsuji. “Ant Reproductive Strategies.” Researches on Population Ecology, vol. 37, no. 2, 1995, pp. 135–149., https://doi.org/10.1007/bf02515814.
Monnin, Thibaud, and Christian Peeters. “How Many Gamergates Is an Ant Queen Worth?” Naturwissenschaften, vol. 95, no. 2, 2007, pp. 109–116., https://doi.org/10.1007/s00114-007-0297-0.