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Heliophobius is an ancient subterranean rodent lineage within the family Bathyergidae, that
displays seasonal breeding over a broad geographical range. In East Africa, reproduction in
these solitary mole-rats has been shown to coincide with the long rains, but it is not clear
whether Heliophobius argenteocinereus emini (Noack 1894) from Tanzania is an induced or
spontaneous ovulator. To address this, urinary progesterone was measured every second day
over a period of 132 days in six wild-caught females subjected to three sequential
experimental treatments. In the first, control (C) treatment, females were housed singly for a
period of 44 days, following which non-physical contact (NPC) with a vasectomised male and
then physical contact (PC) with the same vasectomised male, occurred, in each of the
subsequent 44-day treatments. Non-invasive monitoring of ovarian cyclicity confirmed that mean urinary progesterone concentration was higher during PC than during either NPC or C,
despite the fact that the males were vasectomised and incapable of fertilising the females.
Examination of penile morphology revealed that males possess epidermal projections on the
glans penis which probably bring about cervical stimulation during coitus. These findings together with the female progesterone profiles imply the species is an induced ovulator stimulated by penile intromission. |
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