Masters Degrees (Genetics)
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Browsing Masters Degrees (Genetics) by Advisor "Kotze, A."
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Item Open Access Cross-species microsatellite markers for the detection of hybrids in the genus connochaetes(University of the Free State, 2013-07) Wessels, Letecia; Grobler, J. P.; Kotze, A.; Ehlers, K.Black wildebeest (Connochaetes gnou), a species endemic to South Africa, experienced two bottlenecks in the last century and the number of animals ultimately decreased to approximately 300. These bottlenecks led to a decrease in the genetic diversity of black wildebeest populations across South Africa. An additional threat to the genetic integrity of the black wildebeest was discovered between the 1960s and late 1980s, when researchers noted that hybridization between blue and black wildebeest occurs and that these hybrid animals are fertile. Identification of the hybrid individuals is crucial and various molecular techniques were researched, with microsatellite markers proving to be the most successful. The aim of the current study was to investigate the effectiveness of previously identified cross-species microsatellite markers and statistical approaches for the identification of hybrid herds and individuals on various Nature Reserves in the Free State Province as well as privately owned game farms in and around the Province. Two previously identified diagnostic microsatellite markers (BM1824 and ETH10) were used to screen the populations for putative hybrids. The genetic diversity of the black wildebeest populations studied supported earlier findings showing lower genetic diversity in black wildebeest compared to blue wildebeest. The addition of new reference material in the current study revealed that some of the alleles previously assumed to be unique to a specific species were in fact shared between the two species. This reinforced the need to use more reference populations of adequate size. Nominally blue wildebeest alleles were found in five populations on different game farms and Nature Reserves. The presence of these alleles could be an indication that hybrids are present at these localities or alternatively, support the finding that the number and distribution of reference populations should be increased. Assignment of populations to specific clusters using different software programmes revealed that, due to the large amount of genetic material shared between blue and black wildebeest, no clear assignment of individuals to a specific cluster could be obtained. Molecular analysis of two known hybrid animals did indicate that the two microsatellite markers chosen were able to identify first generation hybrids and possibly even second generation hybrids. The study also investigated the persistence of introgression of blue wildebeest genetic material into black wildebeest populations using simulation software. The simulation tests revealed that introgressed alleles could still be detected after ten generations of backcrossing. This has serious implications for the management of hybrid populations. Various recommendations can be made in terms of the future management and conservation of black wildebeest on Nature Reserves and game farms. The most practical approach for dealing with hybrid animals would first be to develop additional molecular techniques for the accurate identification of populations that contain hybrid animals. Positively identified hybrid populations should be kept separate and no introductions of these animals should be made into pure populations. A more drastic approach would be to cull animals with hybrid ancestry. This would however have serious implications on the already reduced level of genetic diversity in the black wildebeest populations. The most pragmatic approach for dealing with hybrid populations would be to keep pure blue and black wildebeest in protected areas and allow black wildebeest with moderate introgression on game ranches exclusively used for sport hunting.Item Open Access Genetic connectivity, population dynamics and habitat selection of the southern ground hornbill (Bucorvus leadbeateri) in the Limpopo province(University of the Free State, 2011-03) Theron, Nicholas Terence; Kotze, A.; Grobler, J. P.; Jansen, R.Southern ground hornbills (Bucorvus leadbeateri) (SGH) are co-operative breeders that occur in groups of 2-9 individuals. Long life spans, large territory sizes (100kmĀ²), and low reproductive rates render these birds vulnerable to threats such as loss of habitat, persecution for their habit of breaking windows through territorial aggression, poisoning and loss of suitable nesting sites. As a result, SGH are listed as vulnerable in the red data book of South Africa as well as globally. The main objective of this study was to contribute to our overall understanding of the ecology and biology of the SGH for conservation planning. Data collection was completed in the nonprotected, semi-arid landscape of the Limpopo Valley from June 2008 - September 2009. The seasonal habitat use by a group of SGH, seasonal abundance (numbers) and biomass (volume) of invertebrates using pitfall and sweep net methods was investigated. Furthermore, a total of eight groups and 23 birds were captured in the Limpopo Valley and different statistical analysis were performed to investigate levels of inbreeding, relatedness, sex-biased dispersal and the effects the recent re-colonisation has had on the genetic structure of SGH in the Limpopo Valley. Finally the genetic variation of the species in the rest of Africa was determined using samples from Kenya, Tanzania and three populations in South Africa namely the Limpopo Valley, Kruger National Park (KNP) and Kwa Zulu-Natal (KZN). Genetic analysis revealed SGH have retained comparatively high levels of genetic diversity, even though there are indications of genetic bottlenecks in the Limpopo, KNP and Kenyan populations. The SGH populations studied were grouped into two clusters corresponding to the geographic origin of samples. The birds from Tanzania and Kenya clustered together while the KNP and KZN birds clustered together with the Limpopo population grouping more or less equally between the Kenyan/Tanzanian and South African populations. A large percentage of genetic variation was found within populations while among population variation was low, indicating there is little molecular evidence for the presence of SGH subspecies. The overall home range of one group was approximately 20 000 ha while seasonal home ranges varied between 5000 ha in winter to 13 500 ha in summer. The response of organisms to environmental variables in this extremely seasonal habitat was further revealed by the positive correlations found between the number of invertebrates with mean monthly maximum and minimum temperatures, and the volume of invertebrates with mean monthly rainfall. No significant differences were found between numbers and volume of invertebrates per order, between sites, which was expected in this homogenous vegetation type dominated by mopani shrub and trees (Colophospermum mopane). The re-colonisation of the Limpopo Valley was shown to have occurred by a number of unrelated individuals. This was demonstrable by very low levels of inbreeding and average relatedness of the population, as well as the favourable levels of heterozygosity across age and sex categories. Within group relatedness was high with juveniles related to at least one parent from their natal group. Insights were also gained into the breeding behaviour of SGH, providing evidence for the first time that SGH are not as monogamous as previously thought, with two instances of extra pair copulations recorded between four groups. This study shows that a holistic approach combining genetic techniques, radio telemetry studies and ecological principles has great potential to further investigate SGH, thereby contributing to the preservation of this enigmatic species of the savannah biome.Item Open Access Genetic management of the baboon population in the Suikerbosrand Nature Reserve(University of the Free State, 2012-10-12) Bubb, Annesca; Ehlers, K.; Kotze, A.; Grobler, J. P.Genetic management has become a critical part of the overall management of nonhuman primate populations. This dissertation describes a genetic analysis of the chacma baboon population at the Suikerbosrand Nature Reserve. The aim of this study was to apply genetic data as a credible tool to contribute to the conservation and management of chacma baboons at Suikerbosrand Nature Reserve. The specific objectives included individual identification, determining genetic relationships and levels of gene flow within- and among the fourteen troops, and to construct a genetic database with individual genotypes of the whole population. A secondary objective of this study was to determine whether it would be feasible to extract DNA from fecal samples collected from a sleeping site and then use the genetic profiles to determine the number of individuals in that specific troop. The current population is estimated to be between 611 and 764 animals. The sleeping site of the Diepkloof troop was used for this part of the study. A panel of eleven human microsatellite markers was used for DNA analysis. DNA profiles from all the blood samples were successfully constructed and could be used to estimate genetic relationships. The level of genetic diversity in the Suikerbosrand baboon population did not differ significantly from that in the outgroup. Thus, the reintroduction of new individuals into the population to maintain acceptable levels of diversity is not an immediate priority. High levels of gene flow were observed between the troops, especially the troops located in the central part of the reserve. In order to ensure high DNA quality from fecal samples collected at the sleeping site, the collection method for fecal samples were optimized (A manuscript based on the work in this section has been accepted for publication in the European Journal of Wildlife Research). The profiles obtained from the fecal samples that were collected at the Diepkloof site corresponded with two of the thirteen profiles from the reference database. The estimated size of the Diepkloof troop is thirty seven individuals. The results show that non-invasive sampling could be a promising alternative for future research on the reserve, as the samples can be used to determine individual profiles. The genetic data collected can be combined with ecological and behavioral information collected form future research to further understand the population structure of the Suikerbosrand chacma baboons and changes that might occur in the population.