Page 99 - University of Pretoria Research Review 2017

Foreword
Introductory Messages
If one can understand the biochemistry of the naked mole-rat and unlock the mechanisms that switch the pathways during oxygen deprivation, increasing and activating the number of brain cells that are able to use fructose, this could hold great promise for humans, improving our chances of survival in extreme situations. Indeed, this could hold promise for people prone to strokes.
Animal Behaviour
The naked mole-rat is a fascinating animal that defies most characteristics of a mammal. Naked mole-rats can live for over 30 years and studies suggest they are immune to cancer. They are also the only cold-blooded mammal. Their social structure resembles that of social insects such as bees, rather than mammals. These model animals hold much promise for science and one day they may provide insights into how to increase human life-spans or how to fight cancers and tumours.
DEVELOPMENT AND CHANGE
PEOPLE AND CONTEXTS
HEALTH AND WELL-BEING
PLANET AND SUSTAINABILITY
Awards
Lead Researchers
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Studying the social life of one of Africa’s iconic animals
Tanja Wolf, Department of Anatomy and Physiology
While there are differences between subspecies and population groups, the giraffe population in Africa is now listed as ‘Vulnerable’ on the International Union for the Conservation of Nature (IUCN) Red List
of Threatened Species. Threats to their survival include habitat loss, fragmentation and poaching.
Dr Tanja Wolf completed her PhD in the Department of Anatomy and Physiology on the stressors in free-ranging male giraffe
(Giraffa camelopardalis), under the supervision of Professors André Ganswindt and Nigel Bennett at the Mammal Research Institute, and Dr Richard Burroughs at the Centre for Veterinary Wildlife Studies. She has subsequently extended her work on environmental, social and anthropogenic influences.
Giraffe occur in a highly flexible ‘fission-fusion’ social system where group compositions can change on a daily basis. Bulls display
a roaming strategy in the search for fertile females. Wolf monitored a population of giraffe in the Pongola Game Reserve in the province of KwaZulu-Natal over the course of a year and collected faecal samples which were analysed for androgen metabolite (fAM) and glucocorticoid metabolite (fGCM) concentrations. The analysis was undertaken at the Endocrine Research Laboratory, led by Professor André Ganswindt.
Faecal analysis is a non-invasive method for studying the physio- logical response of wildlife to a variety of stressors. In co-authored articles published in General and Comparative Endocrinology in 2017, the researchers report that fAM levels are seasonally dependent. Additionally, older bulls showed significantly higher fAM levels than younger bulls, especially during the summer months, a time when many females give birth and become fertile again. When these bulls are in all-male groups, their fAM levels were significantly lower. This is in line with the behavioural findings that the group structure of giraffes changes with the seasons, with bulls tending to associate more in all- male groups during the winter months when mating opportunities and intra-sexual competition for mates are reduced.
The results also showed that older bulls have higher levels of fGCM when they are in mixed-sex groups and sexually active. By contrast,
the younger bulls showed the highest levels of fGCM when they are in all-male groups, which is probably linked to the age-related hierarchy of bulls.
Tanja Wolf