Is the Mahali mole-rat (Cryptomys hottentotus mahali) a spontaneous or induced ovulator?

2020 ◽  
Vol 98 (5) ◽  
pp. 299-305
Author(s):  
D.W. Hart ◽  
K. Medger ◽  
B. van Jaarsveld ◽  
N.C. Bennett
Keyword(s):  
Direct Contact ◽  
Physical Contact ◽  
Corpora Lutea ◽  
Reproductive Suppression ◽  
Subterranean Rodent ◽  
Breeding Female ◽  
Mole Rat ◽  
Cooperatively Breeding ◽  
Reproductive Females ◽  
Unrelated Male

The Mahali mole-rat (Cryptomys hottentotus mahali (Roberts, 1913)) is a social, cooperatively breeding subterranean rodent that breeds aseasonally. Only one female in a colony breeds and the remaining females are reproductively suppressed. When the opportunity arises, these non-reproductive females disperse from the natal colony to escape reproductive suppression and pair up with an unrelated male to start a new colony. This study set out to determine whether female Mahali mole-rats are induced or spontaneous ovulators once separated from the reproductive suppression of the breeding female. Fifteen separated females were subjected to three treatments: housed separately without a male (A), allowed chemical, but not physical, contact with a vasectomised male (NPC), and placed in direct contact with a vasectomised male (PC). Urine was collected from all females under each treatment every 2 days for 40 days. Only females housed in the PC treatment exhibited heightened progesterone concentrations and corpora lutea of ovulation in the ovaries. Furthermore, males possessed epidermal spines on the shaft of the penises that may be used to stimulate the cervix of the female during copulation. These findings suggest that the Mahali mole-rat is an induced ovulator.

Filling in the holes: The reproductive biology of the understudied Mahali mole-rat (Cryptomys hottentotus mahali)

2021 ◽  
Vol 99 (9) ◽  
pp. 801-811 ◽  
Author(s):  
D.W. Hart ◽  
K. Medger ◽  
B. van Jaarsveld ◽  
N.C. Bennett
Keyword(s):  
Reproductive Tract ◽  
Breeding Strategy ◽  
Arid Environments ◽  
Reproductive Suppression ◽  
Mole Rat ◽  
Evolution Of Sociality ◽  
Great Insight ◽  
Cooperatively Breeding ◽  
Males And Females ◽  
Insight Into

African mole-rats have provided great insight into mammalian evolution of sociality and reproductive strategy. However, some species have not received attention, and these may provide further insights into these evolutionary questions. The cooperatively breeding Mahali mole-rat (Cryptomys hottentotus mahali (Roberts, 1913)) is one such species. Body mass, reproductive-tract morphometrics, gonad histology, and plasma reproductive hormone concentrations were studied for breeding and non-breeding males and females over 1 year. This study aimed to discern if this species exhibits a seasonal or aseasonal breeding pattern and whether there is a relaxation of reproductive suppression at any point in the year in non-breeding animals. The pattern of reproductive relaxation during the wetter months is similar to other African mole-rat species. Interestingly, births and pregnant breeding females were recorded throughout the year, thus indicating an aseasonal breeding strategy, despite inhabiting a region that experiences seasonal rainfall. However, there were periods of the year favouring increased reproduction to enable an increased likelihood of offspring survival. This suggests that the Mahali mole-rat may be an opportunistic breeder possibly brought about by the benefits of living in a cooperatively breeding group and potentially moving into more arid environments that were previously unexploited by the genus Cryptomys Gray, 1864.

Seasonal reproduction in the highveld mole-rat, Cryptomys hottentotus pretoriae (Rodentia: Bathyergidae)

2002 ◽  
Vol 80 (5) ◽  
pp. 810-820 ◽  
Author(s):  
L Janse van Rensburg ◽  
N C Bennett ◽  
M van der Merwe ◽  
A S Schoeman
Keyword(s):  
Body Mass ◽  
Reproductive Tract ◽  
Plasma Testosterone ◽  
Breeding Period ◽  
Corpora Lutea ◽  
Seasonal Breeding ◽  
Nonbreeding Season ◽  
Ovarian Histology ◽  
Mole Rat ◽  
Reproductive Females

The highveld mole-rat, Cryptomys hottentotus pretoriae, is a cooperatively breeding rodent that exhibits seasonal breeding and a reproductive division of labour. Body mass, reproductive-tract morphometrics, ovarian histology, and plasma oestrogen and progesterone concentrations were studied for both reproductive and non-reproductive females from 55 colonies, the main objective being to determine the inclination of this species towards seasonal breeding. Offspring are born from July through to November. However, qualitative analysis of ovarian histology revealed that reproductive females retain the potential for ovulation and subsequent production of corpora lutea during the late-summer nonbreeding period (December–March). Seasonal differences were found in ovarian morphometrics and hormone concentrations that are associated with enhanced follicular activation in April and May and subsequent conceptions from July through to November during the breeding period. The nonbreeding period coincides with maximal dispersal opportunities in the summer-rainfall areas inhabited by the highveld mole-rat. Body mass, reproductive-tract morphometrics, testicular histology, and plasma testosterone concentrations were determined for reproductive and non-reproductive males from 37 colonies. Available evidence suggests that there is a gradual increase in testicular mass for reproductive males as the breeding season approaches, but after September the testicular parameters fall. Seminiferous-tubule diameter was significantly greater in reproductive males but exhibited no seasonal variation. Testosterone concentrations were higher in reproductive males. Current data support a lack of gonadal regression in males during the nonbreeding season.

Band Structure and Failures of Reproductive Suppression in a Cooperatively Breeding Carnivore, the Slender-Tailed Meerkat (Suricata Suricatta)

Behaviour ◽  
1997 ◽  
Vol 134 (11-12) ◽  
pp. 827-848 ◽  
Author(s):  
David W. Macdonald ◽  
Sean P. Doolan
Keyword(s):  
Band Structure ◽  
Adult Males ◽  
High Turnover ◽  
Reproductive Suppression ◽  
Suricata Suricatta ◽  
Adult Females ◽  
Reproductive Female ◽  
Band Size ◽  
Cooperatively Breeding ◽  
Reproductive Females

AbstractThe extent to which band structure influences the distribution of breeding activity is unknown for the slender-tailed meerkat Suricata suricatta, a cooperatively breeding mongoose. Here we present the residence histories of three focal bands monitored over ten band-years in the southwestern Kalahari, with less detailed data derived from non-focal bands for a further 20 band-years. Mean total band size early in the breeding season was 10, and mean size excluding juveniles was 6.7. Despite a tendency towards females among juveniles, and males among yearlings and adults, sex ratios within each age class did not significantly deviate from unity, but at the population level there were significantly more adult males than reproductive females. A large proportion (71.6%) of adult females bred, and failures of reproductive suppression occurred in 40% of band years. This incidence was high in all years and was not obviously related to environmental conditions. Bands with more than one reproductive female contained significantly more adults and adult females than bands with only a single reproductive female. There was a strong correlation between numbers of reproductive females and numbers of adult females in a band. Most (68%) subordinate females which bred were aged three years or more. Reproductive competition was strong and there was a negative correlation between numbers of adult females, breeding females or adult males and per capita juvenile production. Meerkat bands are unusual among cooperative breeders because many individuals were non-kin and the relative constancy in band size within and between years masked a high turnover of membership: all animals of known origin aged three years or older, were immigrants, although philopatry was commoner among younger animals. Our data show that meerkats employ a range of reproductive strategies: bands exhibiting a spectrum of reproductive suppression coexist, and individuals respond to the opportunities afforded by their social environments.

scholarly journals The Cost of Reproduction in a Cooperatively Breeding Mammal: Consequences of Seasonal Variation in Rainfall, Reproduction, and Reproductive Suppression

2021 ◽  
Vol 12 ◽  
Author(s):  
Paul Juan Jacobs ◽  
Daniel William Hart ◽  
Tobias Suess ◽  
Andries Koch Janse van Vuuren ◽  
Nigel Charles Bennett
Keyword(s):  
Oxidative Stress ◽  
Seasonal Variation ◽  
Cost Of Reproduction ◽  
Dry Season ◽  
Breeding Period ◽  
Wet Season ◽  
Reproductive Suppression ◽  
Mole Rat ◽  
Cooperatively Breeding ◽  
The Cost

Biological investments, such as reproduction, are influenced by both biotic and abiotic factors and their interactions. The trade-off between reproduction and survival has been well established. Seasonally breeding species, therefore, may exhibit variations in these trade-offs, but there is a dearth of knowledge concerning this. This study investigated the physiological cost of reproduction (measured through oxidative stress) across seasons in the cooperatively breeding highveld mole-rat (Cryptomys hottentotus pretoriae), one of the few seasonal breeding mole-rats. Oxidative stress indicates elevated reactive oxygen species (ROS) levels, which can overwhelm antioxidant defences resulting in damaged proteins, lipids and DNA, which overall can reduce longevity and compromise reproduction. Oxidative markers such as total oxidant status (TOS-measure of total peroxides present), total antioxidant capacity (TAC), oxidative stress index (OSI), and malondialdehyde (MDA) are utilised to measure oxidative stress. In this study, breeding and non-breeding male (NBM) and female mole-rats were captured during the dry season (breeding period) and wet season (non-breeding period). There was an apparent cost of reproduction in the highveld mole-rat; however, the seasonality pattern to the cost of reproduction varied between the sexes. Breeding females (BFs) had significantly higher MDA during the breeding period/dry season in comparison to the non-breeding period/wet season; this is possibly a consequence of bearing and nursing offspring. Contrastingly, breeding males (BMs) showed increased oxidative damage in the non-breeding/wet season compared to the breeding/dry season, possibly due to increased activities of protecting their mating rights for the next breeding/dry season, but this was not significant. Interestingly, during the non-breeding period/wet season, non-breeding females (NBFs) are released from their reproductive suppression, which resulted in increases in TOS and OSI, which again indicated that just the mere ability to be able to breed results in a cost (oxidative stress). Therefore we can speculate that highveld mole-rats exhibited seasonal variation in redox balance brought about by variation in abiotic variables (e.g., rainfall), physiology and behaviour. We conclude that physiological changes associated with reproduction are sufficient to induce significant acute oxidative stress in the plasma of female highveld mole-rats, which become alleviated following transition to the non-breeding season/wet period suggesting a possible hormetic effect.

scholarly journals Pattern of ovulation in an ancient, solitary mole-rat lineage: Heliophobius argenteocinereus emini from Tanzania

2017 ◽  
Vol 95 (10) ◽  
pp. 737-743 ◽  
Author(s):  
Jestina V. Katandukila ◽  
Mungo K. Ngalameno ◽  
Georgies F. Mgode ◽  
Armanda D.S. Bastos ◽  
Nigel C. Bennett
Keyword(s):  
East Africa ◽  
Physical Contact ◽  
Seasonal Breeding ◽  
Progesterone Concentration ◽  
Subterranean Rodent ◽  
Mole Rat ◽  
The Family ◽  
Experimental Treatments ◽  
Cervical Stimulation ◽  
Ovarian Cyclicity

The genus Heliophobius Peters, 1846 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 the silvery mole-rat subspecies 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 nonphysical 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. Noninvasive 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.

scholarly journals Gnrh mRNA expression in the brain of cooperatively breeding female Damaraland mole-rats

Reproduction ◽  
2017 ◽  
Vol 153 (4) ◽  
pp. 453-460 ◽  
Author(s):  
Cornelia Voigt ◽  
Nigel C Bennett
Keyword(s):  
Mrna Expression ◽  
Anterior Hypothalamus ◽  
Subterranean Rodent ◽  
Mole Rat ◽  
Hybridisation Signal ◽  
Reproductive Females ◽  
Caudal Level ◽  
The Brain ◽  
Social Suppression

The Damaraland mole-rat (Fukomys damarensis) is a eusocial, subterranean rodent, in which breeding is limited to a single reproductive pair within each colony. Non-reproductive females, while in the confines of the colony, exhibit socially induced infertility. Anovulation is thought to be caused by a disruption in the normal gonadotropin-releasing hormone (GNRH) secretion from the hypothalamus. To assess whether social suppression is associated with alteredGnrhmRNA expression in the brain, we investigated the distribution and gene expression levels by means ofin situhybridization in female breeders and non-breeders from field captured colonies of the Damaraland mole-rat. We found expression ofGnrhmRNA as a loose network in several forebrain areas of female Damaraland mole-rats with the majority of labelling in the preoptic and anterior hypothalamus. The distribution matched previous findings using immunocytochemistry in this and other social mole-rat species. Quantification of the hybridisation signal revealed no difference between breeding and non-breeding females in the average optical density of the hybridization signal and the size of the total area covered byGnrhmRNA. However, analysis along the rostro-caudal axis revealed significantly elevatedGnrhmRNA expression in the rostral preoptic region of breeders compared to non-breeders, whereas the latter had increasedGnrhmRNA expression at the caudal level of the anterior hypothalamus. This study indicates that social suppression affects the expression ofGnrhmRNA in female Damaraland mole-rats. Furthermore, differential regulation occurs within different neuron subpopulations.

scholarly journals Reproductive suppression in female cooperatively breeding cichlids

2008 ◽  
Vol 4 (6) ◽  
pp. 606-609 ◽  
Author(s):  
Dik Heg
Keyword(s):  
Clutch Size ◽  
Group Living ◽  
Egg Laying ◽  
Alloparental Care ◽  
Large Female ◽  
Egg Mass ◽  
Small Female ◽  
Reproductive Suppression ◽  
Cooperatively Breeding ◽  
Female Subordinate

Suppression by dominants of female subordinate reproduction has been found in many vertebrate social groups, but has rarely been shown experimentally. Here experimental evidence is provided for reproductive suppression in the group-living Lake Tanganyika cichlid Neolamprologus pulcher . Within groups of three unrelated females, suppression was due to medium- and small-sized females laying less frequently compared with large females, and compared with medium females in control pairs. Clutch size and average egg mass of all females depended on body size, but not on rank. In a second step, a large female was removed from the group and a very small female was added to keep the group size constant. The medium females immediately seized the dominant breeding position in the group and started to reproduce as frequently as control pairs, whereas clutch size and egg mass did not change. These results show that female subordinate cichlids are reproductively capable, but apparently suppressed with respect to egg laying. Nevertheless, some reproduction is tolerated, possibly to ensure continued alloparental care by subordinate females.

Behavioral and demographic changes following the loss of the breeding female in cooperatively breeding marmosets

2000 ◽  
Vol 48 (2) ◽  
pp. 137-146 ◽  
Author(s):  
C. Lazaro-Perea ◽  
C. S. S. Castro ◽  
R. Harrison ◽  
A. Araujo ◽  
M. F. Arruda ◽  
...  
Keyword(s):  
Demographic Changes ◽  
Breeding Female ◽  
Cooperatively Breeding

scholarly journals Social contact behaviors are associated with infection status for whipworm (Trichuris sp.) in wild vervet monkeys (Chlorocebus pygerythrus)

2020 ◽  
Author(s):  
Brandi Wren ◽  
Ian S. Ray ◽  
Melissa Remis ◽  
Thomas R. Gillespie ◽  
Joseph Camp
Keyword(s):  
Direct Contact ◽  
Sickness Behavior ◽  
Gastrointestinal Parasites ◽  
Physical Contact ◽  
Parasitic Infections ◽  
Vervet Monkeys ◽  
Infection Status ◽  
Social Grooming ◽  
Mammal Species ◽  
Chlorocebus Pygerythrus

AbstractSocial grooming in the animal kingdom is common and serves several functions, from removing ectoparasites to maintaining social bonds between conspecifics. We examined whether time spent grooming with others in a highly social mammal species was associated with infection status for gastrointestinal parasites. Of six parasites detected, one (Trichuris sp.) was associated with social grooming behaviors, but more specifically with direct physical contact with others. Individuals infected with Trichuris sp. spent significantly less time grooming conspecifics than those not infected, and time in direct contact with others was the major predictor of infection status. One model correctly predicted infection status for Trichuris sp. with a reliability of 95.17% overall when the variables used were time spent in direct contact and time spent grooming others. This decrease in time spent grooming and interacting with others is likely a sickness behavior displayed by individuals with less energy or motivation for non-essential behaviors. This study highlights the need for an understanding of a study population’s parasitic infections when attempting to interpret animal behavior.

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