Beukes, Dylan Edmund2020-09-142020-09-142019Beukes, Dylan Edmund. (2019). Consequences of grazing resistance adaptations on Rhodohypoxis baurii var. platypetala population genetics. University of the Witwatersrand, https://hdl.handle.net/10539/29642https://hdl.handle.net/10539/29642A Dissertation submitted to the Faculty of Science, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science Johannesburg, Johannesburg 2019Biodiversity in the Drakensberg is threatened by the expansion of farmlands exposing species to intense livestock grazing disturbance, which negatively impacts survival and sexual reproduction in plants, and subsequently the genetic diversity of populations. Assessing the vulnerability of species to grazing is required to ensure effective management of the biodiversity in the region, and this requires an integrated investigation of morphology and genetics. This study aimed to assess the vulnerability of the near-endemic herb Rhodohypoxis baurii var. platypetala to grazing. Morphological difference was investigated by comparing traits between populations at 4 grazed and 4 ungrazed sites. Flower height was found to be 8mm (±2.94mm) taller in plants at ungrazed sites (P = 0.009) and had one more leaf on average (P < 0.001). Other traits, leaf table height, leaf length, number of flowers, leaf angle and above:below ground ratio did not show difference with grazing exposure. These results showed that R. baurii var. platypetala was not developing architecture that would facilitate grazing resistance. The small magnitude of the differences found along with the lack of observed grazing or evidence of grazing suggested that R. baurii var. platypetala plants are not affected by grazing disturbance. The genetic investigation used AFLPs to measure genetic diversity within a population exposed to grazing and another not exposed to the disturbance. It was expected that populations of R. baurii var. platypetala exposed to grazing would have relatively lower genetic diversity and high differentiation. Expectations were not supported as genetic diversity was found to be moderate and similar in the population at the grazed site (HJ = 0.345) and the ungrazed site (HJ = 0.361). An AMOVA found low differentiation between the populations (ΦPT = 0.096) which is attributed to their recent establishment in the area. The moderate genetic diversity and low differentiation showed that it is unlikely that grazing is having a negative impact on the gene dynamics of R. baurii var. platypetala. Comparison of the findings identified significant difference in morphology between the pair of populations, despite their low genetic differentiation and similarly moderate genetic diversity. With one population having 14.10mm taller flowers, 15.14mm taller leaf table height, and 13.35mm longer leaves (all P < 0.001), the morphological difference was extensive but as it was not reflected on a genetic level, it is likely attributed to phenotypic plasticity. The integration of two forms of investigation allowed for comprehensive assessment of the vulnerability of R. baurii var. platypetala to livestock grazing. The results of both investigations aligned to show no negative impacts associated with grazing exposure, and an overall unlikelihood of grazing affecting the plants. The assessment framework is recommended for application in assessing other Drakensberg flora.Online resource (various pagings)enGenetic polymorphismsHemophilia--GeneticsThesis