Faculty of Natural and Agricultural Sciences
School of Biological Sciences
Department of Zoology and Entomology
Selected Highlights from Research Findings
Dr Peter Best, in collaboration with Prof Bruce Mate of Oregon State University, showed that satellite tracked right whales re-utilised a spring/ summer feeding ground in St Helena Bay, last known as a whaling ground in the late eighteenth century. For the first time the routes and destinations of migrations of right whales once they leave the South African coast in spring were revealed, including an unexpected amount of 'commuting' between feeding grounds in the Subantarctic and Antarctic. Shore-based observations of Heaviside's and dusky dolphins showed marked differences in attendance patterns inshore that were presumably related to different foraging strategies.
Contact person: Dr PB Best.
Further south, Prof Marthán Bester and students completed the analyses and published the results of the southern elephant seal mark-recapture study (1983 – 2000) and the comprehensive investigation (1973 – 2000) on killer whales at Marion Island. The first ever comprehensive survey of the fur seal populations at the neighbouring Prince Edward Island was done in December 2001.
Contact person: Prof MN Bester.
The dung beetle research group has, possibly for the first time ever, managed to have an insect group as an indicator of environmental quality written into an ISO regulation. The project, co-funded by industry and THRIP, investigated the feasibility of using dung beetles as indicators of pasture health on selected stock farms in South Africa. The livestock group who solicited the research have written dung beetle monitoring of pasture health into their ISO 9002 regulations, as part of a general regulation on farming in an environmentally friendly, 'natural' way. This has major implications for marketing of livestock, particularly for the export market since 'natural' products fetch a premium price. At present the EU is a major purchaser of 'naturally' produced red meat from South Africa.
Contact person: Prof CH Scholtz.
Professor Rudi van Aarde continued to direct the activities of the Conservation Ecology Research Unit. Research focussed on the elephant as a flagship entity for the development of a regional conservation management plan that may benefit biological diversity across most southern African countries. Projects undertaken on elephants in conservation areas in Namibia, Zambia, Mozambique and South Africa focus on variables that will enable the development of a meta population model through which source and sink interaction can be restored so as to limit population growth. Rudi's research programme on the restoration of coastal dune forests along the coastline of KwaZulu-Natal has been continuing for ten years and is now providing the information through which convergent and divergent patterns of development can be recognised. As an outdoor laboratory the study site is providing a unique opportunity for postgraduate research.
Contact person: Prof RJ van Aarde.
African sunbirds are the ecological equivalent of American hummingbirds. Apart from the fascination of the bird-flower associations, nectar-feeding birds are excellent models for ecophysiological research because their energetics and water turnover are extreme and inseparable. Unlike hummingbirds, passerine nectarivores such as sunbirds forage mainly on dilute nectars, rich in glucose and fructose but poor in sucrose (e.g. Aloe species), and an hypothesis to explain the correlation between nectar concentration and sucrose dominance in bird-pollinated flowers has been tested here on sunbirds and in the USA on hummingbirds. We have also examined how sunbirds cope with a daily water turnover which can be up to five times their body mass.
Contact person: Prof SW Nicolson.
A comprehensive virus sequence database has been established for the three endemic SAT serotypes of foot-and-mouth disease (FMD) and for serotype O in southern Africa. This database permitted accurate determination of the origin of illegally moved FMD-infected buffalo in South Africa, provided insight into the origin of the SAT-type outbreaks in 2000 and 2001 and revealed that the FMD outbreak in KwaZulu Natal in 2000 was caused by an exotic virus introduced from Asia. Phylogenetic analysis of VP1 gene sequences of FMD viruses from the Kruger National Park have also provided the first evidence for natural transmission of the disease between African buffalo (Syncerus caffer) and impala (Aepyceros melampus). In addition, the possibility of sexual transmission of FMD in African buffalo was identified for the first time.
Contact person: Dr AD Bastos.
Recent morphometric analyses suggest that the Namaqua rock mouse, Aethomys namaquensis, in southern Africa may be split into four subspecies, the distribution of which broadly coincides with major phyto-geographic regions of southern Africa. This reduces the number of subspecies based on classical morphology from 16 to 4. The findings have recently been confirmed using molecular data. While the last 20 years or so has witnessed the discovery of many cryptic species of rodents in southern Africa, the geographic distributions of these species is uncertain. By using positively identified material based on molecular, cytogenetic and GIS techniques, it has been possible to delineate the accurate geographic distributions of two of the most enigmatic species, A. chrysophilus and A. ineptus, in southern Africa. These findings have implications in medicine and agriculture as these species have been implicated in causing epidemiological and agricultural problems.
Contact person: Prof CT Chimimba.
The Social Insect Research Group is lead by Prof RM Crewe. The research is mainly focused on honey bees and ponerine ants. For the ponerine ants, species lacking the queen caste are a favoured subject, investigating pheromones and behaviours used in reproductive regulation. For the honey bees, one focus point is the Capensis problem, which is extremely damaging for the beekeeping industry. We have found the cause of the problem - the Capensis pseudo-clone, a parasitic strain of Capensis workers. Workers of the pseudo-clone attack and reproduce in the hives of African bees, using pheromones to mimic the queen and eventually control the hive. Control of the problem is being investigated in co-operation with beekeepers by minimizing the spread between hives. The Varroa mite is a second pest that is of concern to the beekeepers, and is spreading fast throughout South Africa. We fear it can cause a major breakdown of the wild population of honey bees. We are busy assessing the density of the wild population in the Kruger National Park, before damage is done by the mites. Furthermore, we are adjusting varroa treatment strategies to South African conditions, and trying to develop new tools for the control of the mites.
Contact person: Prof RM Crewe.
My research is focused on the ecology of large mammals in African savannas, and over the past year my students and I have been particularly active in Kruger (South Africa) and Chobe (Botswana) national parks. Our studies in Kruger confirm that bovine tuberculosis (BTB) in African buffalo herds is linked to (a) reduced body condition and (b) increased endoparasite load in the dry season. Implications are that buffalo herds with high BTB prevalence could be significantly and suddenly reduced during droughts, and the exposure of lions to tuberculosis is inevitably increasing through their tendency to select out weak individuals from buffalo herds. In Chobe we have found that habitat segregation occurs between elephant bachelor and breeding groups in the dry season but the usual explanation of intersexual scramble competition does not apply. Rather, it appears that conflict avoidance among bulls is the most likely reason, with non-musth bulls avoiding the congregations of breeding groups that occur along the Chobe River in the dry season, because this is where highly aggressive musth bulls are concentrated. Also in Chobe, we have found that elephants are only one of the herbivores driving woodland dynamics. Our telemetry studies and exclosure experiments have demonstrated that impalas preferentially feed in elephant-impacted habitats and browsing at current impala densities results in almost 100% mortality of seedlings of slow-growing riparian trees. An important management implication is that elephant culling will not be effective in promoting the regeneration of riparian woodlands in that ecosystem.
Contact person: Prof JT du Toit.
The mole-rat research group has conclusive evidence that eusociality in a mammal has arisen, not as a result of inbreeding and high relatedness as suggested for the naked mole-rat, but can also occur through outbreeding in the Damaraland mole-rat. Further, the group has shown that endogenous opioid peptides cannot be implicated in the social suppression of subordinate female Damaraland mole-rats. Continued support that rainfall is a trigger for the relaxation of reproductive suppression has been found in this species.
Two distinct methods of ovulation have been found in two phylogenetically closely related mole-rat species in the genus Cryptomys. Finally, in the solitary Namaqua dune mole-rat, a non-invasive method for determining reproductive seasonality in wild animals has been developed.
Contact person: Prof NC Bennett.
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