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.

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.

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.

Reproductive behavior of the blind mole-rat (Spalax ehrenbergi) in a seminatural burrow system

2000 ◽  
Vol 78 (4) ◽  
pp. 570-577 ◽  
Author(s):  
Irit Gazit ◽  
Joseph Terkel
Keyword(s):  
Reproductive Behavior ◽  
Spalax Ehrenbergi ◽  
Mole Rat ◽  
Management Protocol ◽  
In Captivity ◽  
Set Up ◽  
Tunnel System ◽  
Insight Into ◽  
Significant Factors ◽  
Lengthy Process

The blind mole-rat (Spalax ehrenbergi) is a fossorial mammal that is solitary and highly aggressive in nature. The consequent difficulties of maintaining this species in captivity have hindered attempts to gain insight into its behavior and reproductive biology. This article describes an innovative artificial tunnel system and management protocol that facilitated our study of the reproductive behavior of the blind mole-rat in captivity. The study employed a naturalistic approach that allowed the animals to establish separate territories in a seminatural tunnel system and to become familiar with each other over a period of months. This approach contrasts with previous unsuccessful attempts in which mole-rats were introduced without a period of acclimation to each other or to the experimental set-up. The results reveal that both the length of acquaintance between a pair of mole-rats and their own control of the timing of encounters are the most significant factors in reducing aggression and stress. Courtship in blind mole-rats is a lengthy process during which the animals gradually become accustomed to one another, which leads to a reduction of aggression and the initiation of positive "contact movements," eventually enabling copulation to occur. Minimal disturbance by the researcher and initiation of encounters by the mole-rats themselves appear to be the factors that led to a successful mating, pregnancy, and, 34 days later, to the female giving birth and rearing the pups in captivity.

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.

scholarly journals Preparing for battle? Potential intergroup conflict promotes current intragroup affiliation

2010 ◽  
Vol 7 (1) ◽  
pp. 26-29 ◽  
Author(s):  
Andrew N. Radford
Keyword(s):  
Group Dynamics ◽  
Intergroup Conflict ◽  
Breeding Pair ◽  
Simple Consequence ◽  
Future Planning ◽  
Social Contracts ◽  
Evolution Of Sociality ◽  
Cooperatively Breeding ◽  
Intergroup Conflicts ◽  
Agonistic Support

Groups of human soldiers increase their affiliative behaviour when moving into combat zones. Despite numerous other species also competing as groups, little is known about how potential intergroup conflict might influence current intragroup affiliative behaviour in non-human animals. Here, I show that allopreening (when one individual preens another) increases in groups of cooperatively breeding green woodhoopoes ( Phoeniculus purpureus ) when they enter areas where conflicts with neighbours are more likely. Self-preening, which is an indicator of stress in other species, did not increase in conflict areas, suggesting that the change in affiliative behaviour is not the simple consequence of greater stress. Instead, because it is the dominant breeding pair that increase their preening of subordinate helpers, it is possible that current affiliative behaviour is being exchanged for agonistic support in any intergroup conflicts that might ensue. These results are important for our understanding of group dynamics, cooperation and the evolution of sociality, but also bring to mind the intriguing possibilities of social contracts and future planning in birds.

scholarly journals Müllerian inhibiting substance contributes to sex-linked biases in the brain and behavior

2009 ◽  
Vol 106 (17) ◽  
pp. 7203-7208 ◽  
Author(s):  
Pei-Yu Wang ◽  
Anna Protheroe ◽  
Andrew N. Clarkson ◽  
Floriane Imhoff ◽  
Kyoko Koishi ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Reproductive Tract ◽  
Behavioral Traits ◽  
Spinal Motor Neurons ◽  
Müllerian Inhibiting Substance ◽  
Males And Females ◽  
Brain And Behavior ◽  
And Behavior ◽  
The Brain ◽  
Mullerian Inhibiting Substance

Many behavioral traits and most brain disorders are common to males and females but are more evident in one sex than the other. The control of these subtle sex-linked biases is largely unstudied and has been presumed to mirror that of the highly dimorphic reproductive nuclei. Sexual dimorphism in the reproductive tract is a product of Müllerian inhibiting substance (MIS), as well as the sex steroids. Males with a genetic deficiency in MIS signaling are sexually males, leading to the presumption that MIS is not a neural regulator. We challenge this presumption by reporting that most immature neurons in mice express the MIS-specific receptor (MISRII) and that male Mis−/− and Misrii−/− mice exhibit subtle feminization of their spinal motor neurons and of their exploratory behavior. Consequently, MIS may be a broad regulator of the subtle sex-linked biases in the nervous system.

scholarly journals On the effects produced upon the air cells of the lungs when the pulmonary circulation is too much increased

1833 ◽  
Vol 2 ◽  
pp. 321-321
Keyword(s):  
Pulmonary Circulation ◽  
The State ◽  
Great Insight ◽  
Morbid Anatomy ◽  
Air Cells ◽  
Insight Into

In examining the air cells of the lungs of a hare that had been coursed, the author found the superficial large cells filled with colourless coagulable lymph, forming white specks, and the smaller, more interior ones filled with coagula of red blood. No such appearance was seen in the lungs of hares, snared or shot. A run of fifteen minutes with greyhounds so exhausts the hare, that it is frequently known to die from over exertion before the dogs are able to reach it. To examine the state of the lungs, in which the white specks were seen, they were injected with mercury through the bronchiæ, and then immersed in rectified spirits to prevent them from collapsing, and in this state examined microscopically and drawn by Mr. Bauer. The drawings accompany the paper. The white specks appear to be portions of coagulable lymph, separated from the circulating blood in consequence of its disturbed state, and the author considers them as giving great insight into the nature of that destructive disease called tubercles in the lungs; and in support of this idea quotes Dr. Baillie’s description, and refers to his plates of them in his Morbid Anatomy.

scholarly journals Arne Noe-Nygaard 30/7/1908 – 3/6/1991

1991 ◽  
Vol 152 ◽  
pp. 9-10
Author(s):  
K Ellitsgaard-Rasmussen
Keyword(s):  
Geological Museum ◽  
Great Insight ◽  
The University ◽  
Insight Into

Arne Noe-Nygaard died on June 3rd 1991, almost 81 years old; he had then been active as a geologist for 64 years. From 1942 until his retirement in 1978 Noe Nygaard was attached to the University of Copenhagen, as Director of the Mineralogical Museum (now Geological Museum), 1969–77 as Professor of Mineralogy, 1942–69, and as Professor of Dynamic Geology, 1969–78. Noe-Nygaard's great insight into the multifarious world of geology, combined with his friendly, sincere and extrovert nature, made him many influential contacts.

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.

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