Faculty of Natural and Agricultural Sciences
School of Biological Sciences
Department of Zoology and Entomology
Selected Highlights from Research Findings
In 2005, Prof JD Skinner (Wildlife Research Unit, Faculty of Veterinary Science) and Prof CT Chimimba (Mammal Research Unit (MRI), Department of Zoology and Entomology) co-revised the Third Edition of the The mammals of the southern African sub-region, which has subsequently been published by Cambridge University Press.
This new edition contains detailed descriptions of all mammals that occur naturally on the African mainland south of the Zambezi and Cunene Rivers, together with all mammals indigenous to the subregion’s coastal waters.
The rapid accumulation of new information resulting from mammal research in southern Africa, together with radical taxonomic changes across all levels of mammalian classification, necessitated this new edition, which presents the best and latest data accurately in one comprehensive volume for use not only by scientists, but also by an increasingly wide audience of general readers with an interest in the natural history of southern Africa.
The publication, historically considered a prestige project by the University was considered by Cambridge University Press as their flagship publication amongst a 1 000 or so publications in 2005.
Other research highlights in 2005 included the publication (Animal Conservation) of an investigation of a simple measure of taxonomic diversity that can be used as a proxy for different measures of phylogenetic diversity in determining species of regional conservation priority.
Research findings suggested that the inclusion of different measures of phylogenetic diversity may not add value to that currently provided by the taxonomic diversity.
Additional research highlights included the publication (African Zoology) of the most inclusive phylogeny of the enigmatic, but medically and agriculturally important rodent genus Aethomys. Findings are concordant with recent molecular data and suggest that the genus may actually be paraphyletic and strongly supports the taxonomic elevation of the currently recognised subgenera Aethomys and Micaelamys to full generic rank.
Prof CT Chimimba
Zoology and Entomology
+27 (0) 12 420 2752
ctchimimba@zoology.up.ac.za
Research on two OIE List A diseases, foot-and-mouth disease (FMD) and African swine fever (ASF), was undertaken in collaboration with the ARC-Onderstepoort Veterinary Institute. Findings indicate that the genetic diversity of African swine fever virus is far greater than previously documented.
At least 22 viral genotypes have been identified, grouped within three geographically distinct lineages. Although no vaccine is presently available with which to combat this viral hemorrhagic disease, these findings suggest that vaccine developers need to be cognisant of the need to incorporate regionally distinct vaccine strains for vaccination to be effective.
A retrospective analysis of the role of impala in precipitating FMD outbreaks in cattle has shown that this species plays an important intermediary role in transmitting disease between carrier buffalo and susceptible domestic species. This has implications for control of the disease and requires that fences separating buffalo and cattle be sufficiently high to prevent movement of large antelope.
Dr ADS Bastos
Zoology and Entomology
+27 (0) 12 420 4612
amanda.bastos@up.ac.za
It has long been suspected that dung beetles actually feed on small particles of dung obtained from the more fluid parts of the dung and not the dung per se, but there was no known mechanism for empirically measuring the size of food particles that they ingest.
Neither was it known whether the beetles crushed larger food masses to obtain the required size particles, or whether they simply filtered them from liquid food. In collaboration with colleague Peter Holter from the University of Copenhagen in Denmark, a technique was developed for testing the sizes of particles that beetles can actually ingest.
In a simple process of mixing tiny latex balls of very precise sizes - that are used commercially in the paint industry - in food samples, feeding them to captive beetles and then comparing the percentage of latex balls in a sample of food with that in a gut sample, the researchers were able to determine the limits of ingested particles very precisely.
They found that all groups of dung beetles ingest minute food particles, which probably consist of fungal spores, cells sloughed from the gut wall of the animal that produced the dung and other virtually liquid components of the dung.
For comparison, if one were to extrapolate from a dung beetle to an adult of about 100kg in weight, that person would feed on a soup of particles no bigger than 1mm in diameter!
The researchers also proved conclusively that the beetles filter the food from the liquid portion of the dung and that they do not crush larger fractions.
Prof CH Scholtz
Zoology and Entomology
+27 (0) 12 420 3236
chscholtz@zoology.up.ac.za
Missing a meal, or an opportunity to mate, may have short-term effects on survival and fitness, but nothing reduces future fitness quite so completely as being killed and eaten by a predator. As a result, most organisms have effective defence or avoidance tactics when faced with predators. One of the most extreme tactics is to voluntarily shed a limb or appendage to escape a predator.
Crickets will shed, or autotomise, limbs when grasped, and the researchers found that in the field up to 20% of the population have lost one leg, and about 2% have lost three legs.
Rather than the immediate survival value of this extreme behaviour, what interested the researchers were the costs involved with autotomy. In a series of experiments the researchers induced autonomy of either the two middle legs or the two back legs of male and female crickets and found that cumulative loss of legs reduced escape speed, and ability to mate, but not competitive behaviour between males.
Loss of legs also reduced male, but not female, longevity. In addition, the researchers found that loss of a leg made crickets less likely to escape a predator in a subsequent encounter, and that males who had lost a leg became more wary, taking longer to resume singing after a disturbance.
Most interestingly the researchers were able to show that crickets have control over when to shed legs in an encounter with a predator: virgin females who need both of their ears (tympana on the front legs) to locate singing males take longer to autotomise an entrapped front leg than mated females for whom the tympana are no longer so important.
Overall, the researchers were able to demonstrate a range of cost and benefit decisions for an organism and show a connection between reproductive behaviour and anti-predator behaviour.
Dr PW Bateman
Zoology and Entomology
+27 (0) 12 420 2016
phillip.bateman@up.ac.za
The Conservation Ecology Research Unit (CERU) focuses on the restoration of ecological processes to conserve and maintain biological diversity. Presently, CERU maintains two major programmes, the one focusing on regenerating coastal dune forests and the second on restoring spatial dynamics for African elephants.
The publication of a series of papers to evaluate regeneration success is certainly a highlight of the 12 years of research endeavour on the coastal dune systems north of Richards Bay. Through these endeavours, restoration ecologists now have a tool to evaluate the rates of forest regeneration. In addition, ecologists have the statistical procedures to pinpoint aberrant patterns within species collections and within sites in forests.
Restoring the spatial needs of elephants makes conservation sense. This provides the elephant with the roles of a flagship and umbrella for conservation initiatives. During 2005, CERU strengthened its research on elephants across Namibia, Botswana, South Africa, Malawi, Zambia and Mozambique.
The unit’s comparative approaches consider both elephant spatial use and population demography. To this end researchers utilise satellite-tracking techniques to track elephant herds through southern Africa in order to evaluate key factors that underlie range use.
CERU is also pioneering a new technique that allows researchers to measure elephant demographic variables efficiently. The program is attracting considerable attention, both nationally and internationally. CERU’s research findings are key to the development of new conservation paradigms for the management of elephants.
Prof RJ van Aarde
Zoology & Entomology
+27 (0) 12 420 2753
rjvaarde@zoology.up.ac.za
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