Bennett N C, Faulkes C G, Molteno A J
Department of Zoology and Entomology, University of Pretoria, R.S.A.
Proc Biol Sci. 1996 Nov 22;263(1376):1599-603. doi: 10.1098/rspb.1996.0234.
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.
达马拉兰鼹形鼠（Cryptomys damarensis）表现出极端的生殖分工。群体中的繁殖仅限于一对繁殖个体，这是由两方面的控制导致的：（i）垂体促黄体生成素的合成和/或分泌减少，导致非繁殖雌性排卵受阻；（ii）对与熟悉亲属交配的强烈抑制。在有繁殖雌性存在的情况下，非繁殖雌性的促黄体生成素基础循环浓度以及对单次外源性促性腺激素释放激素刺激的反应所测得的促黄体生成素水平，显著低于没有繁殖雌性的群体中的非繁殖雌性。在移除繁殖雌性之前，非繁殖个体的尿孕酮浓度显著高于移除后的值。来自同胞与非同胞配对的行为学研究为强烈的乱伦回避提供了证据，这可能是由于对与熟悉的群体成员交配的抑制所致。总共四对非同胞配对产生了交配行为并最终受孕。相比之下，四对同胞组合均未产生任何性行为或后代。因此，除了在有繁殖雌性存在时对生育能力的生理抑制外，熟悉度的掩盖效应阻止了乱伦，这使得这些非繁殖性地下囊鼠科动物的繁殖抑制变得复杂。
