Female reproductive activity and its endocrine correlates in the African lesser bushbaby, Galago moholi

Abstract

Steroid hormones play an important role in female reproductive physiology and behaviour and are often used to monitor important female reproductive events. However, such studies are often attempted on captive populations alone, delivering limited data. One such example is the African lesser bushbaby, Galago moholi, for which contradicting observational data exist between captive and free-ranging populations, while hormonal analyses have only been obtained from a single captive population. To extend and rectify the limited information, we monitored faecal progestagen and oestrogen metabolite levels across various important life history stages of both captive and free-ranging G. moholi. We additionally recorded changes 2 in vaginal state as well as the occurrence of reproductive and aggressive behaviour throughout the study. Data from our captive population revealed an ovarian cycle length of 33.44 ± 0.59 days (mean ± SD), with follicular and luteal phases of 14.2 ± 1.0 and 19.1 ± 1.5 days, respectively, and an average pregnancy length of 128 ± 3.3 days. The initiation of female reproductive activity was closely linked to an oestrus-related increase in faecal oestrogen metabolite levels. Four of the seven captive females monitored in our study conceived during the May mating period, with one additional female fertilised in September, supporting the idea that the September mating period functions as a back-up for female G. moholi. Identified benchmark faecal progestagen metabolite levels (non-pregnant: > 1 µg/g dry weight (DW), pregnant: > 9 µg/g DW) should help researchers to determine pregnancy-status of randomly wild-caught females in even a cross-sectional study set-up.

Putative drivers of adrenocortical activity in captive African lesser bushbaby (Galago moholi)

“…Although the fGCM patterns were highly variable and presumably chronically elevated as a result of the captive setup of our study, no disruption of reproductive function was found in five of the seven captive females. As the stress response and the effect of chronically elevated stress is individual specific (Romero 2002), the suppression of reproductive function could have occurred for two of the seven females, both showing irregularity in terms ovarian hormone cycles (Scheun et al 2016b). …”

“…Male and female G. moholi individuals have separate, but overlapping, home ranges, with frequent interaction occurring among individuals (Bearder & Martin 1979). G. moholi has been described as polygynandrous, with two mating periods per year (May and September; Pullen, Bearder & Dixson 2000;Scheun et al, 2016b). Our study animals comprised seven male and female individuals held in captivity at IPS, as well as 14 males and 12 females from the surrounding wild population of Buffelsdrift Conservancy.…”

“…The seven adult male and female G. moholi were housed in mating pairs in separate cages at IPS. Although this pairing of G. moholi individuals is unnatural, compared to the natural social structure of the species (Bearder and Martin 1979), this was done to observe mating instances as well as track reproductive hormone patterns in the species during mating and pregnancies (Scheun et al 2016b). The average age of the seven captive females was 3.4 ± 1.3 years of age (range: 2-5 years), while males were 2.9 ± 0.7 years of age (range: 2-4) years old.…”

“…Reliability of the EIA for monitoring adrenocortical activity has been shown in (Scheun et al 2015). EIA parameters, as well as biological validations, for the fAM, fEM and fPM are given in Scheun et al (2016a) and (Scheun et al 2016b). We conducted all assays at the Endocrine Research Laboratory at the Faculty of Veterinary Science, University of Pretoria.…”

“…During the May mating event all seven male and females were involved in mating activity, with four females conceiving. However, as a result of ongoing pregnancies during the September mating event, only three of the seven females were observed mating with their paired males (see Scheun et al 2016b for more information on mating activity). Mating activity in the free-ranging population was observed during the same period, though for only a brief period of time compared to the captive setup (2 days in total).…”