The pattern of reproduction in the mole-rat Heliophobius from Tanzania : do not refrain during the long rains!

Abstract

The genus Heliophobius comprises of at least six cryptic, topotypical species in the Heliophobius argentocinereus species complex. The current study investigated the breeding patterns of a wildcaught population from Tanzania where the putative species H. emini resides. Individuals were collected on a monthly basis for an entire calendar year. Assessment of foetus presence, gonadal histology, reproductive tract morphometrics in combination with gonadal steroid (plasma progesterone and oestradiol-17β in females and testosterone in males) measurements and field observations revealed that rainfall is important for the onset of breeding. The results further confirmed that breeding is limited to a single, yearly reproductive event synchonised to the long rainfall pattern. The distinct breeding peak in July is associated with an elevation in gonadal mass, increase in concentrations of reproductive hormones and presence of Graafian follicles and corpora lutea in the ovaries of females. These reproductive parameters coincided with the end of the long rainfall period, whereas presence of young in the maternal burrow system corresponded with the start of the short rainfall of East Africa. These findings confirm Heliophobius has a single breeding opportunity each year, and this species is therefore vulnerable to any changes that may impact their climatically attuned breeding patterns.