Inaugural Addresses (Botany and Zoology)

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    Ecomorphological forms in Dwarf Chameleons (Bradypodion): assessment of functional morphology and gene flow across spatially adjacent habitat types
    (Stellenbosch : Stellenbosch University, 2013-03) Potgieter, Daniel Francois; Tolley, Krystal; Jansen van Vuuren, Bettine; Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology.
    ENGLISH ABSTRACT: Adaptive radiation is the process whereby clades, lineages, or species demonstrate rapid divergence into an array of phenotypic forms. Variation in ecological parameters, such as habitat use and morphology or behavioural traits related to communication; drive the evolution of ecologically relevant traits in specific habitat types. Nevertheless, such processes may be countered or enhanced by sexual selection pressures as selection acts on the phenotype to maximise reproductive output. Within the Cape Floristic region, species of dwarf chameleons (Bradypodion) are showing signs of such an adaptive radiation. Previous work on B. pumilum revealed intraspecific morphological differentiation, emphasised by functional differences in ecologically relevant traits, between those occupying the fynbos and forest/riverine thicket habitat types. Similar phenotypic divergences are hypothesised to have occurred in their allopatric, forest-dwelling neighbour, the Knysna Dwarf Chameleon (B. damaranum), given the presence of a closely related, morphologically divergent, undescribed species (B. sp. 1) found in the adjacent fynbos habitat type. With this in mind, functional morphological variation was examined between these two potential ecomorphological forms. A second unidentified fynbos species (B. sp. 2), which neighbours these species in its distribution, served to substantiate the proposed morphology~performance~habitat hypotheses. Given the chameleon’s strong reliance of vegetation type, habitat use was explored by examining the microhabitat relevant to chameleons and ascertaining whether this habitat is used randomly. To associate variation in morphology with differences in habitat use, differences in performance capabilities were quantified, particularly those associated with grip strength (hand and tail) and sprint speed. Furthermore, twelve microsatellite markers were used in combination with the ND4 mitochondrial marker to understand the fine scale patterns of gene flow both within and between habitat types. In response to the varied pressures experienced, differences in ecologically relevant traits are found between B. damaranum and the two fynbos species, particularly those related to locomotion (limb length) and bite force (head width). Furthermore, analysis of microhabitat features shows that the fynbos and forest habitat types are structurally different, facilitating differences in habitat use. Differences in performance also vary between vegetation types, with B. damaranum possessing stronger hand and tail grip forces as well as faster sprint speeds. Sexual dimorphism is also present; however it is more prominent in the forest-dwelling B. damaranum. Genetic analyses revealed high levels of geographical structure between B. sp. 1 and B. damaranum, suggesting the presence of a strong barrier to gene flow. Given the congruence between morphological divergence and genetic spatial patterns, it appears that this barrier is associated with habitat type. Within each habitat type, both mtDNA and microsatellite analyses reveal congruent patterns of structuring. These patterns are, however, not governed by barriers to gene flow, but rather via isolation by distance (based on microsatellite data). Furthermore, mtDNA analysis confirmed B. sp. 2 to be highly divergent, occupying a separate clade to B. sp. 1 and B. damaranum. The adaptive differences observed between B. damaranum and B. sp. 1, coupled with its overall resemblance to those observed in B. pumilum; suggest the presence of true chameleon ecomorphs in the genus Bradypodion. This coupled with the lack of gene flow between ecomorphs is indicative of a true allopatric diversification.
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    A journey through the biological complexity of the Cape Floristic Region, South Africa
    (Stellenbosch : Stellenbosch University, 2014-03) Dreyer, Leanne Laurette
    Léanne Dreyer’s fascination with nature started in her pre- ‘‘school years, and has increased steadily throughout her life. She was attracted by the different smells, colours, textures and shapes nature offered, and by the true beauty often revealed in the smallest details. This led her to enrol for a BSc degree at Stellenbosch University, majoring in Botany and Genetics. Her honours and MSc degrees in Botany at the same university focused on the systematics of Pelargonium, a large genus within the biologically rich Cape Floristic Region (CFR). After completing her MSc degree she was appointed as scientist by the South African National Biodiversity Institute (SANBI) in Pretoria, and she enrolled for a PhD at the University of Pretoria under the supervision of Prof AE van Wyk. Her dissertation focused on the palynological diversity of Oxalis, another of the large CFR plant genera. She was appointed by SANBI as South African Botanical Liaison Officer at the Royal Botanical Gardens, Kew (London) during the first year of her PhD studies. After completion of her PhD she was appointed as Postdoctoral Fellow in the laboratory of Prof Peter Linder at the University of Cape Town, and then as lecturer at Stellenbosch University in 1998. Her subsequent research career focused on the diversity and evolution of CFR biota, with a special focus on Oxalis. In 2005 she became a core team member of the NRF/DST Centre of Excellence in Tree Health Biotechnology. This led to an expansion of her research focus to include the fascinating plant-fungus-arthropod interactions prevalent within the CFR.
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    Tall tales from small animals: diversity, phylogeny and biogeography of neglected Southern African arthropods
    (2015-04) Daniels, Savel
    Professor Savel Daniels matriculated from Diazville Senior Secondary School in Saldanha in 1991. Subsequently, he graduated with a BSc degree in 1995, a BSc (Hons) in 1996 and an MSc (cum laude) in 1998 from the University of the Western Cape. In 1999 he was awarded a freestanding merit bursary from the National Research Foundation (NRF) and enrolled for a PhD at Stellenbosch University (SU). During this period, he also received a SU merit bursary and a Harry Crossly bursary. Upon completion of his PhD in 2002, he was appointed as junior lecturer and promoted to lecturer the following year in the SU Department of Botany and Zoology. He was awarded a Claude Leon Foundation postdoctoral fellowship that would have permitted him to undertake postdoctoral research in South Africa. However, he declined this fellowship in favour of a two-year (2004–2005) NRF-funded postdoctoral fellowship in the United States of America to work under the supervision of Prof K. Crandall. Prof. Daniels returned to the Department of Botany and Zoology at SU and became a senior lecturer in 2006 and an associate professor in 2009. His field of expertise is molecular systematics, phylogeography and the conservation of invertebrates. The main objective of his work is to better understand and document the spectacular biological diversity of South Africa to aid the conservation of these groups. Professor Daniles received a Fulbright Research Scholarship and an Oppenheimer Memorial Trust Research Grant for his sabbatical at Harvard University during 2012. He was promoted to full professor at SU as from 1 January 2014.