Naked mole-rats (Heterocephalus glaber) do not specialise in cooperative tasks

It has been proposed that naked mole-rat (Heterocephalus glaber) societies resemble those of eusocial insects by showing a division of labour among non-breeding individuals. Earlier studies suggested that non-breeders belong to distinct castes that specialise permanently or temporarily in specific cooperative tasks. In contrast, recent research on naked mole-rats has shown that behavioural phenotypes are continuously distributed across non-breeders and that mole-rats exhibit considerable behavioural plasticity suggesting that individuals may not specialise permanently in work tasks. However, it is currently unclear whether individuals specialise temporarily and whether there is a sex bias in cooperative behaviour among non-breeders. Here, we show that non-breeding individuals vary in overall cooperative investment, but do not specialise in specific work tasks. Within individuals, investment into specific cooperative tasks such as nest building, food carrying and burrowing is positively correlated, and there is no evidence that individuals show trade-offs between these cooperative behaviours. Non-breeding males and females do not differ in their investment in cooperative behaviours and show broadly similar age and body mass related differences in cooperative behaviours. Our results suggest that non-breeding naked mole-rats vary in their overall contribution to cooperative behaviours and that some of this variation may be explained by differences in age and body mass. Our data provide no evidence for temporary specialisation, as found among some eusocial insects and suggest that the behavioural organisation of naked mole-rats resembles that of other cooperatively breeding vertebrates more than that of eusocial insect species.

Automated summary

Our study shows that non-breeding naked mole-rats vary in overall cooperative investment, but do not specialize in specific work tasks. Investment in specific cooperative tasks within individuals is positively correlated, with no evidence of trade-offs between these behaviors. Non-breeding males and females do not differ in their investment in cooperative behaviors and show similar age and body mass related differences in cooperative behaviors, suggesting that the behavioral organization of naked mole-rats resembles that of other cooperatively breeding vertebrates more than that of eusocial insect species.