Reproductive suppression in subordinate, non-breeding female Damaraland mole-rats: two components to a lifetime of socially induced infertility.
The Damaraland mole-rat Cryptomys damarensis exhibits an extreme reproductive division of labour. Reproduction in the colony is restricted to a single breeding pair, resulting from a two-fold control: (i) a reduced pituitary synthesis and/or secretion of luteinizing hormone leading to a block to ovulation in non-reproductive females; and (ii) a strong inhibition to breeding with familiar kin. Circulating basal concentrations of luteinizing hormone as well as luteinizing hormone levels measured in response to a single exogenous gonadotrophin releasing hormone challenge, were significantly lower in non-reproductive females in the presence of the reproductive female than those in colonies lacking a reproductive female. Urinary progesterone concentrations before the removal of the reproductive female were significantly higher in non-reproductives than the post removal values. Behavioural studies from sib-sib and non-sib pairings provide evidence for a strong incest avoidance, probably resulting from an inhibition of breeding with familiar colony members. A total of four pairings of non-sibs resulted in copulatory activity and eventual conception. In contrast, four couples of sib-sib combinations failed to produce any sexual activity or offspring. Thus, suppression of reproduction in these non-reproductive, subterranean bathyergids is complicated by the masking effect of familiarity that prevents incest, in addition to the physiological inhibition of fertility in the presence of the reproductive female.
Bennett
N C
NC
Department of Zoology and Entomology, University of Pretoria, R.S.A.
Faulkes
C G
CG
Molteno
A J
AJ
D000818:Animals; D003404:Creatinine / Q000652:urine; D005260:Female; D005298:Fertility; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D011374:Progesterone / Q000652:urine; D012098:Reproduction; D012377:Rodentia / Q000502:physiology*; D012726:Sexual Behavior, Animal; D012919:Social Behavior
D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D007986:Luteinizing Hormone; D003404:Creatinine