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Energetics reveals physiologically distinct castes in a eusocial mammal


Eusociality, which occurs among mammals only in two species of African mole-rat, is characterized by division of labour between morphologically distinct ‘castes’1. In Damaraland mole-rats (Cryptomys damarensis), colony labour is divided between ‘infrequent worker’ and ‘frequent worker’ castes2. Frequent workers are active year-round and together perform more than 95% of the total work of the colony, whereas infrequent workers typically perform less than 5% of the total work3. Anecdotal evidence suggests that infrequent workers may act as dispersers, with dispersal being limited to comparatively rare periods when the soil is softened by moisture4,5. Here we show that infrequent workers and queens increase their daily energy expenditure after rainfall whereas frequent workers do not. Infrequent workers are also fatter than frequent workers. We suggest that infrequent workers constitute a physiologically distinct dispersing caste, the members of which, instead of contributing to the work of the colony and helping the queen to reproduce, build up their own body reserves in preparation for dispersal and reproduction when environmental conditions are suitable.

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Figure 1: Resting metabolic rate and daily energy expenditure for C. damarensis.


  1. Jarvis, J. U. M., O'Riain, M. J., Bennett, N. C. & Sherman, P. W. Mammalian eusociality: a family affair. Trends Ecol. Evol. 9, 46–51 (1994)

    Article  Google Scholar 

  2. Bennett, N. C. & Jarvis, J. U. M. The social structure and reproductive biology of colonies of the mole-rat Cryptomys damarensis (Rodentia: Bathyergidae). J. Mamm. 69, 293–302 (1988)

    Article  Google Scholar 

  3. Bennett, N. C. & Faulkes, C. G. African Mole-rats Ecology and Eusociality 273 (Cambridge Univ. Press, Cambridge, 2000)

    Google Scholar 

  4. Hazell, R. W. A., Bennett, N. C., Jarvis, J. U. M. & Griffin, M. Adult dispersal in the cooperatively breeding Damaraland mole-rat, Cryptomys damarensis: a case study from the Waterberg region of Namibia. J. Zool. 252, 19–26 (2000)

    Article  Google Scholar 

  5. Jarvis, J. U. M. & Bennett, N. C. Eusociality has evolved independently in two genera of bathyergid mole-rats—but occurs in no other subterranean mammal. Behav. Ecol. Sociobiol. 33, 353–360 (1993)

    Article  Google Scholar 

  6. Stacey, P. B. & Koenig, W. D. Cooperative Breeding in Birds (Univ. Cambridge press, Cambridge, 1990)

    Book  Google Scholar 

  7. Solomon, N. G. & French, J. F. Cooperative Breeding in Mammals (Cambridge Univ. Press, Cambridge, 1997)

    Google Scholar 

  8. Emlen, S. T. in Behavioural Ecology an Evolutionary Approach 4th edn (eds Krebs, J. R. & Davies, N. B.) 228–253 (Blackwell, Oxford, 1997)

    Google Scholar 

  9. Emlen, S. T. in Behavioural Ecology an Evolutionary Approach 2nd edn (eds Krebs, J. R. & Davies, N. B.) 301–337 (Blackwell, Oxford, 1991)

    Google Scholar 

  10. Keller, L. & Reeve, H. K. Partitioning of reproduction in animal societies. Trends Ecol. Evol. 9, 98–102 (1994)

    CAS  Article  Google Scholar 

  11. Waterman, J. M. Mating tactics of male Cape ground squirrels, Xerus inauris: consequences of year-round breeding. Anim. Behav. 56, 459–466 (1998)

    CAS  Article  Google Scholar 

  12. O'Riain, M. J., Jarvis, J. U. M. & Faulkes, C. G. A dispersive morph in the naked mole-rat. Nature 380, 619–621 (1996)

    ADS  CAS  Article  Google Scholar 

  13. Speakman, J. R. Doubly Labelled Water, Theory and Practice (Chapman and Hall, London, 1997)

    Google Scholar 

  14. Scantlebury, M., Oosthuizen, M. K., Speakman, J. R., Jackson, C. R. & Bennett, N. C. Seasonal field energetics of the Hottentot golden mole (Ambysomus hottentotus longiceps) at 1500m altitude. Physiol. Behav. 84, 739–745 (2005)

    CAS  Article  Google Scholar 

  15. Hammond, K. A. & Diamond, J. Maximal sustained energy budgets in humans and animals. Nature 386, 457–462 (1997)

    ADS  CAS  Article  Google Scholar 

  16. Bennett, N. C., Jarvis, J. U. M. & Davies, K. C. Daily and seasonal temperatures in the burrows of African rodent moles. S. Afr. J. Zool. 23, 189–195 (1988)

    Article  Google Scholar 

  17. Burland, T. M., Bennett, N. C., Jarvis, J. U. M. & Faulkes, C. G. Eusociality in African mole-rats: new insights from patterns of genetic relatedness in the Damaraland mole-rat. Proc. R. Soc. Lond. B 269, 1025–1030 (2002)

    Article  Google Scholar 

  18. Molteno, A. J. & Bennett, N. C. Relaxation of socially-induced reproductive inhibition in colonies of the eusocial Damaraland mole-rat: the effect of aridity as an ecological constraint promoting philopatry. J. Zool. 256, 445–448 (2002)

    Article  Google Scholar 

  19. Jacobs, D. S., Bennett, N. C., Jarvis, J. U. M. & Crowe, T. M. The colony structure and dominance hierarchy of the Damaraland mole-rat, Cryptomys damarensis (Rodentia: Bathyergidae) from Namibia. J. Zool. 224, 553–576 (1991)

    Article  Google Scholar 

  20. Hardy, R. N. Temperature and Animal Life. The Institute of Biology. Studies in Biology no. 35 (Arnold, London, 1972)

    Google Scholar 

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This research was funded by the National Research Foundation, Republic of South Africa (N.C.B.) and a University of Pretoria Post Doctoral Research Fellowship (M.S.). We thank S. van Cutsem and H. Hjarvard de Fine Licht for assistance in the field, and F. Dalerum and G. Gutjahr for comments on the manuscript. Experimental procedures and animal husbandry practices were approved by the Animal Ethics Committee, University of Pretoria. Author Contributions M.S., conception of research, fieldwork, organization of study site, data analysis and manuscript preparation; J.R.S., isotope analysis and contribution to manuscript preparation; M.K.O., fieldwork; T.J.R., conception of research and contribution to manuscript preparation; N.C.B., conception of research, fieldwork, organization of study site, acquisition of funding and contribution to manuscript preparation.

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Correspondence to M. Scantlebury.

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Scantlebury, M., Speakman, J., Oosthuizen, M. et al. Energetics reveals physiologically distinct castes in a eusocial mammal. Nature 440, 795–797 (2006).

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