Naked mole rats go to war. The sociable little mammals have been observed invading neighbouring populations and even kidnapping newborn pups, who become workers in the conquering colony.
The rats (Heterocephalus glaber) are one of a handful of mammal species that are eusocial: they live in large underground colonies in which most members are sterile workers and only one individual, the queen, reproduces. They have been compared with eusocial insects like honeybees.
Stan Braude at Washington University in St Louis, Missouri, and his colleagues made crucial observations of the rats attacking their neighbours in the early 1990s, but didn鈥檛 have the genetic technology to confirm what they suspected had happened at the time.
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The researchers were tracking colonies of naked mole rats in Meru National Park, Kenya, and noticed 26 examples of colonies expanding their territory into burrows previously occupied by other colonies.
As part of their study, the team repeatedly captured entire colonies, marked each animal, then returned them to their burrows. This allowed the researchers to track individual naked mole rats over successive years.
In May 1994, they began capturing two neighbouring colonies and noticed that the queen of one had wounds on her face, suggesting that the second colony had attacked. They returned the animals to their burrows, but the following year they found two pups from the attacked colony living as workers in the other one.
For years, Braude suspected he had simply made a mistake. 鈥淲e just didn鈥檛 have the tools to make sure that I hadn鈥檛 totally screwed up,鈥� he says. Now, genetic analyses of tissue samples from the original animals have confirmed that the pups really had ended up in a different colony. It seems the pups became completely integrated into their new home, although it isn鈥檛 clear whether they ever had the opportunity to reproduce.
Journal of Zoology
