TEMPORAL CHANGES IN THE SOCIAL-STRUCTURE OF A CAPTIVE COLONY OF THE DAMARALAND MOLE-RAT, CRYPTOMYS DAMARENSIS - THE RELATIONSHIP OF SEX ANDAGE TO DOMINANCE AND BURROW-MAINTENANCE ACTIVITY

Crytomys damarensis is a eusocial subterranean rodent occurring in col onies in which a sole reproductive female and one to two males are inv olved in procreation; the remaining colony members are nonreproductive . Within each sex the reproductive animals are usually the largest and most dominant animals. The dominance hierarchy of a young colony cons isting of a founding reproductive pair of genetically unrelated animal s and the first three successive litters, comprising 12 offspring, fro m this pair had a nonlinear dominance hierarchy, h = 0.32. Dominance w as found to be correlated positively to body mass as well as to the ag e of the animal. A subsequent study, which followed the incorporation of two subsequent litters and growth of the first three litters, and c omprised 15 offspring, revealed that the dominance hierarchy had attai ned linearity, h = 0.9. Dominance was again positively correlated with the age and body mass of respective colony members. In both studies t here was no clear relationship between dominance and sex within the co lony. The relationship between body mass and burrow-maintenance activi ty revealed that frequent workers in the colony had a greater mean bod y mass than infrequent workers. It is suggested that in establishing c olonies, the older, stronger and hence larger animals may constitute t he initial workforce. In addition the colony exhibits frequency-relate d work determination into frequent and infrequent workers. Gender was found to play no role in the frequency of work associated with burrow maintenance. The social organization and temporal changes with recruit ment are discussed in the light of events occurring in the field.