DIFFERENTIAL GROWTH-PATTERNS BETWEEN SUCCESSIVE LITTERS OF THE EUSOCIAL DAMARALAND MOLE-RAT, CRYPTOMYS DAMARENSIS, FROM NAMIBIA

Differential mean rates of growth were calculated for successive litte rs of mole-rats born to genetically unrelated pairs of C. damarensis. The Logistic equation provided the closest fit to the growth data. Bot h intra- and inter-colonial variation in mean maximum growth rate betw een successive litters incorporated into the natal colonies were deter mined. The mean asymptote (A), growth rate constant (K) and inflection time(I) were modelled for the first five litters of pups born to pair s of mole-rats. Inter-colonial analysis of recruitment to colonies rev ealed litters 1, 2, and 5 to grow faster than litters 3 and 4. Litters 1 and 2 had significantly higher asymptotes and inflection times than litters 3, 4, and 5 (P < 0.001). All litters were assimilated into th eir natal colonies. There were no significant differences between male s and females for the asymptote. growth rate constant; or inflection t ime (P > 0.05). Intra-colonial variation of litters 1 to 4 born to a s ingle colony revealed comparable results to that obtained for inter-co lonial comparisons. Multiple comparisons showed litters 1 and 2 to hav e a significantly higher absolute growth rate than litters 3 and 4. Th e lowest rate of growth being for litter 4. The patterns of mean diffe rential growth are discussed in the light of the social organization o f the colony. It is postulated that growth rates in litters 1, 2, and 3 are more rigid since they constitute the main functional unit of col ony organization. Litters 4 and 5 show a greater plasticity in growth; it is speculated that these colony members become incorporated into t he various worker and defender groupings which are characteristic of C . damarensis colonies.