Nepotism in ants - ant workers can recognize their kin

Darwin in his time wondered about the existence of ants - how can natural selection as a process based on individual reproductive success give rise to sterile individuals such as ant workers? The solution comes from kin selection theory, which holds that an individual's reproductive success can also be measured in the number of collateral kin produced. This is how the ants have solved the problem. In an ant colony with only one queen all the workers are her offspring and will in practice help to raise their siblings, which are genetically as valuable to them as own offspring.

However, colonies with multiple reproductively active queens occur commonly in ants. As a result workers will also be raising the more distantly related offspring, produced by queens other than their own mother. This dilutes the genetic returns from the help the workers provide. By selectively favouring offspring of the queen of closest kin, the workers can, however, partly mitigate this loss and more efficiently propagate their genes to the next generation. Because it is the workers who raise the brood they also have the opportunity to favour closer kin and disfavour (e.g. eliminate) more distant kin. Such nepotism has not been demonstrated before in ants.

Professor Liselotte Sundström and scientist Minttumaaria Hannonen studied black ants and found out that kin does matter, and relatedness is also a matter of discrimination. Their article is published in Natute, 27th of February, 2003.

  • Reference: Liselotte Sundström, Minttumaaria Hannonen, 'Worker Nepotism among polygynous ants', Nature 27.2.2003.

  • Professor Liselotte Sundström, Department of Ecology and Systematics,

News of the month »»
News archive »»
University of Helsinki