- I obtained my PhD in 2006 from Stellenbosch University on a project that focused on the ecology of a genus of fungi a... moreI obtained my PhD in 2006 from Stellenbosch University on a project that focused on the ecology of a genus of fungi associated with South African Protea spp. After finishing a two-year position as postdoctoral fellow at the internationally highly-regarded Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, I accepted a position as lecturer at the Department of Conservation Ecology and Entomology, Stellenbosch University during June 2008 and was appointed as core team member of the DST/NRF Centre of Excellence in Tree Health Biotechnology (CTHB). I now head the Diversity and Symbiosis Research Group at this department with the major focus of how fungi interact with other organisms in the Cape Floristic Region.
Life did not take over the globe by combat, but by networking. This view of the natural world, the way in which all organisms interact with one another to make the machinery of life work properly has long been a research focus of numerous scientists. These symbioses between organisms are often a major driving force in the evolution on life on earth. At the Department of Conservation Ecology and Entomology of the University of Stellenbosch, the Diversity and Symbiosis research group, headed by myself, focuses on the diversity and interactions of fungi, plants and arthropods in the Cape Floristic Region (CFR). This group has been involved in the discovery and description of more than fifty new species of fungi, ten new plant species and about ten arthropod species in the CFR. However, most work focus on unraveling the mysteries of how organisms interact with one another and how they can co-exist. One of these systems involves the interactions between fungi, mites, insects, birds, bacteria and fungi within the fruiting structures of Protea.. These fruiting structures can be viewed as “mini ecosystems” and are seen as ideal systems for testing ideas on community ecology. Amongst other things this research group has described how fungi that live within these “cones” have evolved special spores and specialized associations with mites to help them to disperse from one habitat to the next using insects and even birds at “taxis”. In other systems, similar fungi have evolved close associations with beetles that chew tunnels into the wood of forest trees. In these systems the fungus serves as the food of the beetle larvae, and may help weaken trees for more beetles to colonize, but in turn, the fungus uses the same beetles to spread between different trees. Whilst these interactions are well known in the Northern Hemisphere, work on these interactions are in its infancy in South Africa and most existing information has been generated by this research group within the Afromontane forests of the southern Cape. One of the more recently discovered systems involves a fungus that has found a way to sterilize its host plant, and to induce this host to produce fungal spores instead of the usual pollen grains. The plant’s normal pollinators, bees, cannot tell the difference between flowers that contain pollen versus flowers that contain fungal spores. The fungus therefore hijacks the plant’s reproductive system and also uses its usual pollinators, to spread infective spores from diseased plants to healthy ones. A second research tier of this group is to investigate arthropod diversity in the CFR, the mechanisms maintaining this diversity and the influence of various parameters on this, including the influence of human alterations of habitats. Most of abovementioned research was conducted in the Fynbos and Afromontane forest Biomes of the Western Cape Province, however, fieldwork was also conducted in numerous other provinces of South Africa including KZN and the Northern- and Southern Cape.edit
Research Interests:
The mating-type (MAT1) locus encodes transcription factors essential for the onset of the sexual cycle in ascomycete fungi. This locus has been characterised in only a few heterothallic, plant pathogenic Mycosphaerellaceae and... more
The mating-type (MAT1) locus encodes transcription factors essential for the onset of the sexual cycle in ascomycete fungi. This locus has been characterised in only a few heterothallic, plant pathogenic Mycosphaerellaceae and Teratosphaeriaceae. We used available genome sequences for Mycosphaerellales species to investigate the presence of two unique mating-type-associated features. The accessory MAT1 genes, MAT1-1-10 (MATORF2) and MAT1-2-12 (MATORF1), typically occurred in both MAT idiomorphs of Mycosphaerellaceae species. In contrast, they were associated with only one idiomorph in Teratosphaeriaceae species. In Pseudocercospora, phylogenetic analyses showed that homologs present in different idiomorphs were paralogous and subject to different selective pressures, indicating that their evolution is linked to mating type. In almost half of the investigated Mycosphaerellales genomes, numerous short fragment sequences, almost identical to portions of the MAT1-1-1 and MAT1-2-1 genes, were present in multiple areas outside of the MAT1 locus. Aligned to the MAT1 genes, these sequences resembled an mRNA transcript. Fragment sequences were similar among species groups and occurred at the same genomic positions, implying that monophyletic groups have the same origins of these sequences. Although the functions of the MAT fragment sequences and accessory MAT1 genes remain unknown, both were expressed in the representative Mycosphaerellaceae and Teratosphaeriaceae species that were investigated.
Research Interests:
Number of individuals per quadrat for hemipteran morpho-species collected on the vegetation at Jonkershoek on December 2014 (six year old vegetation (post-fire age))
Research Interests:
Communities are mostly composed of rare species; yet, the factors that determine their patterns of occurrence remain obscure. Theory predicts that, in contrast with common species, the occurrence of rare species will be poorly correlated... more
Communities are mostly composed of rare species; yet, the factors that determine their patterns of occurrence remain obscure. Theory predicts that, in contrast with common species, the occurrence of rare species will be poorly correlated with environmental variables (niches) and more affected by stochasticity (ecological drift), but how this pattern varies across different trophic groups is still poorly understood. Here, we compared the ability of environmental variables (bottom-up biotic niches) to predict the occurrence of plant-dwelling arthropods across different abundance classes in the Cape Floristic Region of South Africa. We compared three trophic groups, including 104 herbivorous hemipteran, 171 parasitoid wasp and 84 spider species, totalling 4511 individuals in 48 quadrats. To quantify bottom-up biotic niches, we studied the influences of species composition of plants on hemipterans, and of plants and hemipterans on spiders and wasps. We compared the observed strength of the correlation between rare species and their niches with expectations that were generated by repeatedly rarefying abundant species. A large proportion of arthropod species were very rare, i.e. with only 1 or 2 individuals (49-55%). Although rarefying abundant species greatly decreased the correlation with bottom-up biotic niches, bottom-up biotic niches generally better predicted the occurrence of rarefied abundant species than very rare ones, suggesting a greater influence of drift on very rare arthropods. That is, (very) rare arthropods are distributed more randomly than rarefied abundant species. Nevertheless, trophic groups differed in the details of their response to bottom-up biotic niches. Plant species composition was a better predictor of rarefied abundant than truly rare hemipterans. In contrast, the importance of bottom-up biotic niches among abundance classes varied less visibly in spiders and wasps. Our study thus suggests that the importance of niches in structuring arthropod communities depends on species rarity and trophic group
Research Interests:
Two new species of Oxalis (Oxalidaceae) from the Richtersveld are described, namely Oxalis canaliculata and O. magnifolia. These widespread species are morphologically distinct and easily identified, but both contain populations in which... more
Two new species of Oxalis (Oxalidaceae) from the Richtersveld are described, namely Oxalis canaliculata and O. magnifolia. These widespread species are morphologically distinct and easily identified, but both contain populations in which individuals consistently differ morphologically from typical varieties. The typical variety of Oxalis canaliculata is widespread throughout the Richtersveld, while O. canaliculata var. trifoliolata is known from a single population and O. canaliculata var. graniticola is known only from granite outcrops. Oxalis magnifolia includes the typical variety that is widespread and Oxalis magnifolia var. reduplicata, which is only known from two populations in close proximity to one another. Morphological characters, preliminary phylogenetic position based on data from the nuclear ITS region, habitat description and formal taxonomic descriptions are provided for all taxa. The diagnostic characters of the new species are compared to all phenotypically similar...
Research Interests:
Research Interests: Zoology, Biology, Ecology, Biodiversity, Arthropod, and 4 moreTransect, Species Richness, Shrubland, and Netting
Mean body length (in mm), developmental stage and trophic group of arthropod morpho-species collected on the vegetation at Jonkershoek on December 2014 for a "bird exclosure" experiment
Research Interests:
Table S3. Sequenced Sordariomycete fungi used as evidence for genome annotations. (XLSX 12 kb)
Research Interests:
FIGURE 1. Bayesian analyses 50% majority-rule consensus trees. Parsimony bootstrap support values> 70 % are shown above branches, Bayesian posterior probability values> 0.95 are shown below the branches. The O. pes-caprae clade is... more
FIGURE 1. Bayesian analyses 50% majority-rule consensus trees. Parsimony bootstrap support values> 70 % are shown above branches, Bayesian posterior probability values> 0.95 are shown below the branches. The O. pes-caprae clade is indicated. The two new species are indicated in bold. Bars below trees indicate expected number of substitutions per site. A) tree based on ITS data. B) tree based on trnSG data.
FIGURE 1. Map of localities for new Richtersveld Oxalis taxa. The thick black line indicates both the Orange River and the border between South Africa and Namibia. The thin black line is the coastline. Darker shading indicates higher... more
FIGURE 1. Map of localities for new Richtersveld Oxalis taxa. The thick black line indicates both the Orange River and the border between South Africa and Namibia. The thin black line is the coastline. Darker shading indicates higher elevation. Contour intervals are 150 m.
Additional file 3: Figure S3. Original red-and-green confocal staining images of cross sections of sterilized Oxalis seeds indicating bacteria (bright green rods) inside cavities. (i-ii) O. hirta, (iii) O. pes-caprae.
The Cape Town Hypothesis Test is the third phase of the pilot study for Cape Citizen Science (http://citsci.co.za/), a project to engage non-scientists as pathogen hunters. This phase was initiated because urban environments provide... more
The Cape Town Hypothesis Test is the third phase of the pilot study for Cape Citizen Science (http://citsci.co.za/), a project to engage non-scientists as pathogen hunters. This phase was initiated because urban environments provide opportunities for the early detection of Phytophthora invasions. The hypothesis is that the Phytophthora species in the urban areas of Cape Town are different to those in the less disturbed Table Mountain National Park. Citizens were invited to contribute to the hypothesis test by submitting samples from their backyard as well as a few targeted areas in the urban areas. This is the first citizen-driven microbiology based hypothesis test in South Africa. Cape Citizen Science has already demonstrated the efficacy of engaging non-scientists in microbiological research, but the primary aim of this phase of the project was to demonstrate that citizens can contribute to testing hypotheses. In addition, by empowering citizens as biodiversity “protectors”, this ...
Research Interests:
Research Interests:
Research Interests:
Few economic assessments have been developed to inform national priorities on the management of high-impact, early-stage invasive alien species (IAS). Economic assessments are biased towards ex post assessments of the costs and benefits... more
Few economic assessments have been developed to inform national priorities on the management of high-impact, early-stage invasive alien species (IAS). Economic assessments are biased towards ex post assessments of the costs and benefits of control options and are in need of refinement to deal with potentially vigorous invaders with considerable uncertainty on spread and impact. The Polyphagous Shot Hole Borer (PSHB) beetle represents a potentially high-impact invasion in progress in South Africa. We approached the problem of PSHB invasion in South Africa through (i) interdisciplinary collaboration to reduce uncertainty in economic and biological parameters by defining robust ranges for model parameters and (ii) a simulation model to take account of dynamic mutualistic relations between the beetle and it’s symbiont fungus. We modelled the potential social cost of a PSHB invasion on natural forests, urban trees, commercial forestry and the avocado industry. Our results indicate that t...
Research Interests:
Research Interests:
The aggressive Eucalyptus leaf pathogen, Teratosphaeria destructans, causes widespread damage in tropical and subtropical Eucalyptus‐growing regions of Indonesia, China, Thailand, East Timor, Vietnam, Lao, and South Africa. Little is... more
The aggressive Eucalyptus leaf pathogen, Teratosphaeria destructans, causes widespread damage in tropical and subtropical Eucalyptus‐growing regions of Indonesia, China, Thailand, East Timor, Vietnam, Lao, and South Africa. Little is known regarding the origin, pathways of dispersal, or reproductive biology of this pathogen. The aim of this study was to investigate the genetic structure of a global collection of T. destructans isolates. This was achieved by developing and using polymorphic microsatellite markers. Low genotypic diversity and a limited number of private alleles were found in all investigated populations, with the highest maximum diversity of 10.7% in isolates from South Sumatra. This supports the hypothesis that T. destructans was introduced to these regions. High levels of clonality were common in all populations, especially in isolates sampled from the recent disease outbreak in South Africa, which were all identical. The global collection of isolates grouped into three distinct clusters, corresponding largely to their sampled regions. Low levels of genotypic diversity, high levels of clonality, and strong geographic structure suggest independent introductions into all the sampled areas from an unknown source. The results imply that strict biosecurity measures are needed to avoid introductions of additional genotypes in these areas.
Research Interests:
Research Interests:
Research Interests:
Research Interests: Plant Biology and Ecology
Research Interests:
Research Interests: Biology, Medicine, Multidisciplinary, PLoS one, Grassland, and 3 moreGrazing, Livestock Grazing, and Herbivore
Oxalis dreyerae, a new species from the arid Richtersveld region of South Africa, is described. It is most similar to O. inconspicua from which it differs, among others, by having a larger plant body, larger and showier flowers with a... more
Oxalis dreyerae, a new species from the arid Richtersveld region of South Africa, is described. It is most similar to O. inconspicua from which it differs, among others, by having a larger plant body, larger and showier flowers with a broadly trumpet-shaped tube, much larger leaflets, petioles that are thicker than the peduncles, much larger lanceolate sepals and short, stubby teeth on the longer filaments. Its placement within the O. flava clade is supported by nrDNA ITS sequence evidence, which is also consistent with a close relationship to O. inconspicua. Oxalis dreyerae represents the eighth described species of Oxalis endemic to the arid Richtersveld of the Northern Cape, thus supporting the importance of the floristically diverse Gariep Centre of Endemism, of which the region forms a part.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Cape Citizen Science (http://citsci.co.za) is a plant disease awareness initiative in South Africa. The pilot study was designed to reveal the diversity and distribution of Phytophthora species in the Cape Floral Kingdom. The project has... more
Cape Citizen Science (http://citsci.co.za) is a plant disease awareness initiative in South Africa. The pilot study was designed to reveal the diversity and distribution of Phytophthora species in the Cape Floral Kingdom. The project has engaged many non-scientists as pathogen hunters and samples have been submitted from several plant producers, botanical gardens, nature reserves, and national parks. Citizen engagement activities have revealed the presence of multiple species of Phytophthora previously undocumented in South Africa and they have facilitated the discovery of at least one novel species. The most recent phase of the project invited citizens to participate in The Cape Town Hypothesis Test, a study designed to promote the early detection of Phytophthora species introductions in urban areas of Cape Town. This pilot study has pioneered the application of several methods of public engagement in plant disease research. Citizens have submitted samples from their home gardens, ...
Novel species of fungi described in this study include those from various countries as follows: Antarctica , Apenidiella antarctica from permafrost, Cladosporium fildesense fromanunidentifiedmarinesponge. Argentina , Geastrum wrightii... more
Novel species of fungi described in this study include those from various countries as follows: Antarctica , Apenidiella antarctica from permafrost, Cladosporium fildesense fromanunidentifiedmarinesponge. Argentina , Geastrum wrightii onhumusinmixedforest. Australia , Golovinomyces glandulariae on Glandularia aristigera, Neoanungitea eucalyptorum on leaves of Eucalyptus grandis, Teratosphaeria corymbiicola on leaves of Corymbia ficifolia, Xylaria eucalypti on leaves of Eucalyptus radiata. Brazil, Bovista psammophila on soil, Fusarium awaxy on rotten stalks of Zea mays, Geastrum lanuginosum on leaf litter covered soil, Hermetothecium mikaniae-micranthae (incl. Hermetothecium gen. nov.)on Mikania micrantha, Penicillium reconvexovelosoi in soil, Stagonosporopsis vannaccii from pod of Glycine max. British Virgin Isles , Lactifluus guanensis onsoil. Canada , Sorocybe oblongispora on resin of Picea rubens. Chile, Colletotrichum roseum on leaves of Lapageria rosea. China, Setophoma caverna...
Research Interests:
Background Plant-endophyte symbioses often revolve around nitrogen metabolism, and involve varying degrees of intimacy. Although evidence for vertical inheritance of nitrogen-fixing endophytic bacteria is increasing, it is confined mostly... more
Background Plant-endophyte symbioses often revolve around nitrogen metabolism, and involve varying degrees of intimacy. Although evidence for vertical inheritance of nitrogen-fixing endophytic bacteria is increasing, it is confined mostly to crop plants, and to date no such system has been reported for geophytes. Methods Bacterial endophytes associated with Oxalis, the most species-rich geophytic genus form the Cape Flora in southern Africa was studied. Culturable endophytes were isolated from surface-sterilized vegetative and reproductive plant organs for six host species at three locations. Colonies of microbes on various artificial media were morphotyped, enumerated and identified using sequence data. Filter exclusion experiments were conducted to determine if endophytes were vertically transmitted to seeds, determine if mucilage plays a role to actively attract microbes from the soil and to assess microbial richness isolated from the mucilage of Oxalis seedlings. Fluorescent mic...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
During a recent survey of Penicillium spp. from fynbos soils in the Western Cape Province of South Africa, several undescribed species were isolated. Similar isolates of one of these species also were collected in the Western Cape from... more
During a recent survey of Penicillium spp. from fynbos soils in the Western Cape Province of South Africa, several undescribed species were isolated. Similar isolates of one of these species also were collected in the Western Cape from Protea infructescences. These strains were compared morphologically to known species of Penicillium but could not be identified with previously published keys. Morphologically these strains belong to subgenus Biverticillium. They are distinguished by strongly funiculose colonies covered by glutinous exudates and conidiophores with thin acerose phialides (8.5-10[-12] x 2.0-2.5 microm) that give rise to chains of subspheroidal to ellipsoidal conidia (2.5-3.0 x 1.5-2.5 microm). Characteristically short (100-150[-250] microm) determinate synnemata are produced in culture after prolonged incubation with much longer synnemata produced in nature. Based on differences in morphology and molecular characters, the strains are described here as Penicillium ramulosum sp. nov.
Research Interests:
Background Plant-endophyte symbioses often revolve around nitrogen metabolism, and involve varying degrees of intimacy. Although evidence for vertical inheritance of nitrogen-fixing endophytic bacteria is increasing, it is confined mostly... more
Background Plant-endophyte symbioses often revolve around nitrogen metabolism, and involve varying degrees of intimacy. Although evidence for vertical inheritance of nitrogen-fixing endophytic bacteria is increasing, it is confined mostly to crop plants, and to date no such system has been reported for geophytes. Methods Bacterial endophytes associated with Oxalis, the most species-rich geophytic genus form the Cape Flora in southern Africa was studied. Culturable endophytes were isolated from surface-sterilized vegetative and reproductive plant organs for six host species at three locations. Colonies of microbes on various artificial media were morphotyped, enumerated and identified using sequence data. Filter exclusion experiments were conducted to determine if endophytes were vertically transmitted to seeds, determine if mucilage plays a role to actively attract microbes from the soil and to assess microbial richness isolated from the mucilage of Oxalis seedlings. Fluorescent mic...
Additional file 1: Figure S1. Seedling germination and development of recalcitrant Cape Oxalis, where foliar leaf development and growth is followed by delayed radicle growth. O. clavifolia Sond. (a) and O. glabra Thunb. (b) one (i),... more
Additional file 1: Figure S1. Seedling germination and development of recalcitrant Cape Oxalis, where foliar leaf development and growth is followed by delayed radicle growth. O. clavifolia Sond. (a) and O. glabra Thunb. (b) one (i), three (ii), five (iii) and 10 (iv) days after germination. All seedlings oriented with radicle pointing to bottom of figure. CT = cotyledons, FL = foliar leaf, RD = radicle.
Research Interests:
The microbial diversity associated with natural vegetation in the Greater Cape Floristic Region of South Africa is largely unexplored. As part of the Cape Citizen Science programme and independent research, surveys were conducted between... more
The microbial diversity associated with natural vegetation in the Greater Cape Floristic Region of South Africa is largely unexplored. As part of the Cape Citizen Science programme and independent research, surveys were conducted between 2015 and 2019 to catalogue the diversity of Phytophthora species associated with many plant species endemic to this region. Using soil and water baiting techniques, six isolates of the provisionally described Phytophthora taxon emzansi were recovered, together with three isolates of an undescribed Phytophthora species. In this study, we used both molecular and morphological data to describe these Phytophthora species. Isolates of P. emzansi sp. nov. and P. afrocarpa sp. nov. formed monophyletic lineages within Phytophthora Clades 2 and 10, respectively. Phytophthora emzansi sp. nov. and P. capensis are sister species residing in the P. citricola species complex, and both are homothallic. Phytophthora afrocarpa sp. nov. is a sister species to P. gall...
Research Interests: Microbiology and Biology
Research Interests:
Replacement of complex assemblages of native mammal fauna with livestock species reduces niche heterogeneity. This negatively affects taxa such as dung beetles, which depend on them and can, in turn, affect ecosystem functioning. We... more
Replacement of complex assemblages of native mammal fauna with livestock species reduces niche heterogeneity. This negatively affects taxa such as dung beetles, which depend on them and can, in turn, affect ecosystem functioning. We assessed the response of dung beetle diversity, biomass and body condition to cattle-farming pressures in protected areas (PAs) and adjacent farms in the savannah biome of northern Namibia. We hypothesized that rich native mammal assemblages are essential to maintain dung beetle diversity and overall biomass. We further explored whether the low-quality dung resources on farms would lead to a decrease in individual body size for species found on both farms and PAs. Overall dung beetle richness increased with higher mammal richness but not relative abundance, demonstrating that a rich native vertebrate assemblage promotes dung beetle richness. Overall dung beetle biomass was lower on farms, but abundance showed no difference. Large-bodied dung specialist s...
Research Interests:
Protea flowers host saprobic Knoxdaviesia and Sporothrix fungi that are dispersed by pollinating insects and birds. Different Protea species contain sympatric populations of different fungal species. For example, P. repens host S.... more
Protea flowers host saprobic Knoxdaviesia and Sporothrix fungi that are dispersed by pollinating insects and birds. Different Protea species contain sympatric populations of different fungal species. For example, P. repens host S. splendens and K. proteae , while P. neriifolia host K. capensis and S. phasma . Even though all fungi can grow vigorously on alternative hosts and they share the same spore vector species, they rarely colonise alternative hosts. We investigated the role of fungal differential competitive abilities on their usual and alternative hosts to explain their host exclusivity. In a de Wit replacement series experiment, S. splendens outcompeted and later overgrew all other fungi on media prepared from its usual and alternative hosts. Host exclusivity of S. splendens on P. repens may therefore be maintained by restricted movement of spore vectors rather than weaker competitive abilities on alternative hosts. On their preferred hosts, S. splendens and S. phasma rapidly overgrew Knoxdavesia species with which they do not usually share a host, explaining host exclusivity of the Knoxdavesia species. Knoxdaviesia proteae likely only persist on P. repens with sympatric S. splendens if it colonizes flowers earlier, in a different area, or completes its life cycle before being overgrown. On their usual P. neriifolia host, K. capensis and S. phasma had neutralistic interactions and S. phasma could not overgrow K. capensis , explaining their co-existence. Host exclusivity of saprobic Protea -associated Knoxdaviesia and Sporothrix may therefore be maintained by both the activities of spore vectors and differential competitive abilities on different hosts, but the influence of other competing microbes and micro-niche differentiation cannot be excluded.
Research Interests:
Female stag beetles (Lucanidae) possess internal mycangia to maintain microbial cultures. Yeasts from these mycangia may help with larval nutrition in nutrient poor woody substrates, but only a few Lucanidae taxa have been studied and all... more
Female stag beetles (Lucanidae) possess internal mycangia to maintain microbial cultures. Yeasts from these mycangia may help with larval nutrition in nutrient poor woody substrates, but only a few Lucanidae taxa have been studied and all reports originate from Europe and Asia. We identify the first mycangial yeasts of a South African endemic Lucanidae beetle, Xiphodontus antilope, using nuclear ribosomal RNA and ITS DNA sequence data. In addition we identified yeasts from the larval gut, fecal matter, frass and woody substrate surrounding larvae and pupae. The mycangium of X. antilope was confined to females and is structurally similar to all other Lucanidae. Unlike most Lucanidae that seemingly associate with single species of yeast, or whose mycangia contain yeast monocultures, three yeast species were commonly isolated from X. antilope. Scheffersomyces coipomoensis was the most numerically dominant species on most substrates and in most individuals, but a second, undescribed, Scheffersomyces species was present in high numbers. A third species, also undescribed and unrelated to Scheffersomyces, was recovered from all mycangia but could not be detected in the larval gut, fecal matter, frass or woody substrates. We confirm a close association of Scheffersomyces yeasts with Lucanidae globally, but other taxa may also be involved. We show that the predominant mycangial yeasts also form the predominant yeasts within the larval gut and the woody substrates around the larvae and pupae. This combined external and internal colonization by the same yeasts may provide enhanced opportunities for nutrient acquisition, but this needs validation in future studies.
Research Interests:
Draft genomes of the fungal species Fusarium xylarioides, Teratosphaeria gauchensis and T. zuluensis are presented. In addition an annotation of the genome of Ceratocystis fimbriata is presented. Overall these genomes provide a valuable... more
Draft genomes of the fungal species Fusarium xylarioides, Teratosphaeria gauchensis and T. zuluensis are presented. In addition an annotation of the genome of Ceratocystis fimbriata is presented. Overall these genomes provide a valuable resource for understanding the molecular processes underlying pathogenicity and potential management strategies of these economically important fungi.
Research Interests:
Abstract Forests are sensitive ecosystems with a distinctive micro-climate to which forest arthropods have adapted. In intact primary forests, sunlight only fully reaches forest floors temporarily through tree fall, or more permanently at... more
Abstract Forests are sensitive ecosystems with a distinctive micro-climate to which forest arthropods have adapted. In intact primary forests, sunlight only fully reaches forest floors temporarily through tree fall, or more permanently at forest edges. Roads that cut through pristine forests are however permanent features that fragment forests and increase forest edge. In accordance with the intermediate disturbance hypothesis (IDH), these edges may allow generalist species to enter forests and replace some specialists, often leading to little change, or even higher numbers of arthropod species at edges. Here, we determined how roads and hiking trails affect epigaeic forest arthropods in the largest Afrotemperate forest complex in South Africa. Arthropods were collected using pitfall traps along transects set up perpendicular to different types of road, including wide arterial roads, narrower secondary roads and hiking trails. As expected, hiking trails affected arthropod assemblages to a much smaller extent than the roads. Edge effects, as measured by arthropod alpha diversity, were evident up to only 5 m for hiking trails yet as much as 20 m for secondary roads and >50 m into the adjoining forest for arterial roads. Our results support the intermediate disturbance hypothesis, as changes in beta-diversity, especially next to arterial roads, was driven by the replacement of species in conjunction with changes in species richness. The magnitude of edge effect was however different for the selected feeding guilds. We recommend that where possible roads and even many hiking trails are removed from many areas of the deep forests. These ancient Afrotemperate forests are fragmented by roads and to a lesser degree by hiking trails, which could have cascading effects on overall forest integrity and long-term impacts on these forests.
Research Interests:
Strip mining in arid ecosystems causes extreme ecological destruction that may take decades to recover. The present study examined the effect of different plant-community rehabilitation treatments on arthropods after strip mining in the... more
Strip mining in arid ecosystems causes extreme ecological destruction that may take decades to recover. The present study examined the effect of different plant-community rehabilitation treatments on arthropods after strip mining in the arid Namaqualand region of South Africa. Vegetation cover and plant species richness were significantly lower at all rehabilitated sites compared with those at a reference site. Arthropod species richness did not differ amongst the different treatments and the reference site. Except for the most recently rehabilitated site, arthropod abundance in all guilds was higher at all treatments compared with that of the reference site. Overall arthropod abundance was positively correlated to plant cover and negatively correlated to plant species richness, but these vegetation characteristics had no effect on arthropod species richness. This may be explained by a high cover of pioneer plants at the rehabilitated sites, which offer ample food for generalist arthropod taxa. Arthropod community composition differed significantly between treatments. We demonstrate that rehabilitation of ecosystem function after mining in arid systems is a lengthy process, even after implementation of intensive rehabilitation protocols. We also show that arthropod communities provide additional insights into the level of ecosystem recovery otherwise obscured when only considering plant community data.
Research Interests:
The inflorescences and infructescences of African Protea trees provide habitat for a large diversity of Sporothrix species. Here we describe two additional members, Sporothrix nsini sp. nov. and Sporothrix smangaliso sp. nov., that are... more
The inflorescences and infructescences of African Protea trees provide habitat for a large diversity of Sporothrix species. Here we describe two additional members, Sporothrix nsini sp. nov. and Sporothrix smangaliso sp. nov., that are associated with the infructescences of various Protea species from grasslands and savannas in the KwaZulu-Natal, North-West, Gauteng and Mpumalanga provinces of South Africa. Their description raises the number of described Protea-associated Sporothrix species to twelve. S. smangaliso sp. nov. is distantly related to other Protea-associated species and, in phylogenies using multiple markers (ITS, beta-tubulin and calmodulin), groups with taxa such as Sporothrix bragantina from Brazil and Sporothrix curviconia from the Ivory Coast. S. nsini sp. nov. resolved as sister to a clade containing four other Protea-associated species within the Sporothrix stenoceras complex. S. nsini sp. nov. was collected from within the same infructescences of Protea caffra ...