Learn More
Mole-rats are strictly subterranean and hardly, if ever, come into contact with external light. As a result, their classical visual system is severely regressed and the circadian system proportionally expanded. The family Bathyergidae presents a unique opportunity to study the circadian system in the absence of the classical visual system in a range of(More)
Comparative studies of two species of mole-rat are helping to clarify the ecological correlates of mammalian eusociality. Both species live in social groups composed of close kin, within which breeding is restricted to one female and one to three males. They inhabit xeric areas with dispersed, patchy food and unpredictable rainfall. During droughts, they(More)
In many animal societies, dominant individuals monopolize reproduction, but the tactics they employ to achieve this are poorly understood. One possibility is that aggressive dominants render their subordinates infertile by inducing chronic physiological "stress." However, this hypothesis has been discarded largely for cooperatively breeding species, where(More)
The Natal mole-rat, Cryptomys hottentotus natalensis, rarely, if ever, is exposed to external light cues because it occurs in completely sealed tunnel systems. As a result, their classical visual system is regressed, and therefore, their circadian system is expected proportionally to be expanded. Locomotor activity was investigated under a number of(More)
In most animals, the sex that invests least in its offspring competes more intensely for access to the opposite sex and shows greater development of secondary sexual characters than the sex that invests most. However, in some mammals where females are the primary care-givers, females compete more frequently or intensely with each other than males. A(More)
The hippocampus is essential for the formation and retrieval of memories and is a crucial neural structure sub-serving complex cognition. Adult hippocampal neurogenesis, the birth, migration and integration of new neurons, is thought to contribute to hippocampal circuit plasticity to augment function. We evaluated hippocampal volume in relation to brain(More)
In animal social groups, socially subordinate individuals frequently show low reproductive success or completely fail to breed. This suppression of subordinate reproduction is currently typically attributed to control by dominant individuals. However, subordinates in cooperative groups often lack access to unrelated mates, and an alternative possibility is(More)
The distribution of orexinergic cell bodies and terminal networks within the brains of two species of African mole rat (Cape-dune mole rat--Bathyergus suillus and highveld mole rat--Cryptomys hottentotus) were identified using immunohistochemistry for orexin-A. The aim of the study was to investigate possible differences in the nuclear complement and(More)
Although humans are diurnal in behaviour, animal models used for the study of circadian rhythms are mainly restricted to nocturnal rodents. This study focussed on the circadian behaviour of a rodent from South Africa that has a preference for daylight, the four-striped field mouse, Rhabdomys pumilio. In order to characterise the behavioural pattern of daily(More)
The Mashona mole rat, Cryptomys darlingi, is a social, subterranean African rodent that is rarely, if ever, exposed to light, and that exhibits a regressed visual system. This study investigated locomotor activity patterns of Mashona mole rats (n=12) under different light cycles. Activity was measured using either infrared captors (n=8) or running wheels(More)