In ants, colonies are normally headed by one or several queens. The workers themselves are sterile and they do lots of different work. When they are young, they take care of the brood. However, when they get older, they take on more risky tasks such as foraging for food. Tasks such as foraging are risky as they involve having to go outside, where there are many dangers lurking around the corner.
Some ants however, have a different life-style. In the dinosaur ant Dinoponera quadriceps, the workers are not sterile, and there is a dominance hierarchy in the colony. This hierarchy is established through ritualized aggressive interactions, resulting in a ranking between the workers. Once the current queen dies, the highest ranking worker will take over the colony. This means there are several ways in which workers can lead a successful life:
1) inherit the colony and make a lot of babies
2) work hard, so that your queen can make a lot of babies
Claire Asher and colleagues looked at how the rank of an individual influences its behaviour. They found that high ranking individuals (the ones that have a bigger chance of inheriting the colony ‘soon’) will not go out to forage, and will not help in defending the colony as much as the lower ranking workers. However, this does not mean they are lazy. They do take on the less risky tasks, such as taking care of the brood.
This is due to the fact that if a high ranking worker would go out to forage, she has a higher chance of dying, and thus would lose all her chances of inheriting the colony. Lower ranking workers don’t have much chance of inheriting the colony anyway, so for them it’s more worthwhile to take on the more risky tasks in order to increase the success of the colony. It all makes sense once you think about it!
Asher, C.L., Nascimento, F.S., Hughes, W.O.H. (2013) Division of labour and risk taking in the dinosaur ant, Dinoponera quadriceps (Hymenoptera: Formicidae). Myrmecological news 18:121-129