Nc. Bennett et al., REPRODUCTIVE SUPPRESSION IN SUBORDINATE, NON-BREEDING FEMALE DAMARALAND MOLE-RATS - 2 COMPONENTS TO A LIFETIME OF SOCIALLY INDUCED INFERTILITY, Proceedings - Royal Society. Biological Sciences, 263(1376), 1996, pp. 1599-1603
The Damaraland mole-rat Cryptomys damarensis exhibits an extreme repro
ductive division of labour. Reproduction in the colony is restricted t
o a single breeding pair, resulting from a two-fold control: (i) a red
uced pituitary synthesis and/or secretion of luteinizing hormone leadi
ng to a block to ovulation in non-reproductive females; and (ii) a str
ong inhibition to breeding with familar kin. Circulating basal concent
rations of luteinizing hormone as well as luteinizing hormone levels m
easured in response to a single exogenous gonadotrophin releasing horm
one challenge, were significantly lower in non-reproductive females in
the presence of the reproductive female than those in colonies lackin
g a reproductive female. Urinary progesterone concentrations before th
e removal of the reproductive female were significantly higher in non-
reproductives than the post removal values. Behavioural studies from s
ib-sib and non-sib pairings provide evidence for a strong incest avoid
ance, probably resulting from an inhibition of breeding with familiar
colony members. A total of four pairings of non-sibs resulted in copul
atory activity and eventual conception. In contrast, four couples of s
ib-sib combinations failed to produce any sexual activity or offspring
. Thus, suppression of reproduction in these non-reproductive, subterr
anean bathyergids is complicated by the masking effect of familiarity
that prevents incest, in addition to the physiological inhibition of f
ertility in the presence of the reproductive female.