Why mole rats are more flexible than we previously thought

Date: August 29, 2016

Source: University of Cambridge

One of the most interesting facts about mole rats -- that, as with ants and termites, individuals specialise in particular tasks throughout their lives -- turns out to be wrong. Instead, a new study led by the University of Cambridge shows that individuals perform different roles at different ages and that age rather than caste membership accounts for contrasts in their behaviour.

Mole rats, including the naked mole rat, live in underground colonies. The majority of rodents in the colonies are 'workers', with only one female (the 'queen') and one male responsible for breeding. All individuals cooperate by digging large underground tunnel systems to forage for food, and if a large food source is found, it is shared with the entire colony. 'Queens' and reproductive males remain in this role for their entire life after they have achieved this position. When a 'queen' dies, the strongest and largest helper is probably the prime candidate for inheriting the breeding position.

Early studies suggested that non-reproducing mole rats can be divided into non-workers, infrequent workers and frequent workers, and that most individuals stay members of distinct castes for their entire lives. Individual mole rats would focus on a particular task, such as digging, nest building or colony defence, throughout their lives.

Now, however, in a study published in Proceedings of the National Academy of Sciences, researchers from the Department of Zoology at the University of Cambridge have shown that in Damaraland mole rats, the contributions of individuals to cooperative activities change with age and that individual differences in behaviour that appeared to be a consequence of differences in caste are, in fact, age-related changes in behaviour. Whether variation in behaviour between naked mole rats is also a consequence of similar age-related changes is not known -- but this seems likely.

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