REPRODUCTIVE-BEHAVIOR IN THE FEMALE BLIND MOLE-RAT (SPALAX-EHRENBERGI)

The mole rat (Spalax ehrenbergi) is a blind, solitary, highly aggressi ve subterranean rodent well adapted to underground life, and in Israel involves four chromosomal species (Nevo, 1998). Little is known to da te about its reproductive biology and all attempts to breed mole rats in captivity have failed. The present study investigated the effects o f three different light regimes on vaginal smear and annual cycle of b ody weight, age at sexual maturity, and various parameters of reproduc tive behaviour of female mole rats. Daily vaginal smears throughout th e year revealed that the mole rat does not have a regular oestrous cyc le, but exhibits an annual rhythm with a seasonally cornified smear. R egardless of the photoperiods the females were exposed to in the labor atory, relatively high proportions of cornified smears were found duri ng the winter breeding season. A second, albeit small, peak of cornifi ed cells was found during the summer season. Photoperiod had no effect on annual body mass cycle either, and mole rats kept under the differ ent lighting regimes reached their maximum weight just prior to the be ginning of the breeding season. In young females, vaginal opening occu rs at the age of four weeks and first cornified smear at the age of 4- 7 months. The presence of a cornified smear was found to be an insuffi cient criterion for receptivity, but providing the opportunity for a f emale to choose her mate enhances the chances of copulations occurring during encounters. We conclude that the mole rat is a seasonal breede r which reproduces during the winter, but has the potential of summer breeding too. Our findings also suggest that females probably have the potential to breed in their first winter. The seasonally constant vag inal smear periods, and the post copulation vaginal smear data are the first evidence suggesting that the mole rat is a reflex ovulator, but the ovulatory failure we observed after single copulations raises the possibility that multiple copulations are necessary to induce ovulati on.