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A synopsis of Emilia (Senecioneae, Asteraceae) in southern Africa
No full textCron, Glynis V. (2014): A synopsis of Emilia (Senecioneae, Asteraceae) in southern Africa. Phytotaxa 159 (3): 195-210, DOI: 10.11646/phytotaxa.159.3.3, URL: http://dx.doi.org/10.11646/phytotaxa.159.3.
FIGURE 3 in A synopsis of Emilia (Senecioneae, Asteraceae) in southern Africa
No full textFIGURE 3. Known distributions of the species of Emilia in southern Africa. (Note that the distribution of E. limosa in East Africa is much greater than shown here.)Published as part of Cron, Glynis V., 2014, A synopsis of Emilia (Senecioneae, Asteraceae) in southern Africa, pp. 195-210 in Phytotaxa 159 (3) on page 207, DOI: 10.11646/phytotaxa.159.3.3, http://zenodo.org/record/512862
FIGURE 1. A–E in A synopsis of Emilia (Senecioneae, Asteraceae) in southern Africa
No full textFIGURE 1. A–E Emilia schinzii: A, B, Lilac and white forms of the capitula; C, cylindrical cypsela with rows of white hairs on the ribs; D, style arms with conical/penicillate apices topped with a tuft of sweeping hairs and surrounded by smaller papillae; E, stamens with narrow acute apical appendage and balusterform filament collar [Cron & Goodman 788 (J)] F, E. marlothiana: slightly succulent 'bushy' herb with solitary capitula on long peduncles, inset: discoid capitulum with creamy white florets; G, E. tenellula: characteristically narrow capitula with florets not much longer than involucral bracts [Miller 4385 (SRGH)]. Scale bars = A 8.9 mm, B 10 mm, C 0.66 mm, D 1.5 mm, E 0.46 mm, F (inset) 5 mm, G 3.3 mm.Published as part of Cron, Glynis V., 2014, A synopsis of Emilia (Senecioneae, Asteraceae) in southern Africa, pp. 195-210 in Phytotaxa 159 (3) on page 199, DOI: 10.11646/phytotaxa.159.3.3, http://zenodo.org/record/512862
FIGURE 2. A–C in A synopsis of Emilia (Senecioneae, Asteraceae) in southern Africa
No full textFIGURE 2. A–C, Emilia protracta: A, habitat at edge of gorge in mist spray overlooking Devil's Cataract, Victoria Falls; B, habit: decumbent red stems - supported by surrounding vegetation at edge of path; C, pair of axillary capitula with maroon florets, slightly succulent leaves tinged purple-red; D–E, E. transvaalensis: D, habit: bushy herb with grey-green leaves; E, ecalyculate capitulum with pale pink disc florets, purple-tipped stamens protruding [McCallum 1050 (J)]. Scale bars: B, 50 mm, C 8 mm, D 8 cm, E 2.7 mm.Published as part of Cron, Glynis V., 2014, A synopsis of Emilia (Senecioneae, Asteraceae) in southern Africa, pp. 195-210 in Phytotaxa 159 (3) on page 205, DOI: 10.11646/phytotaxa.159.3.3, http://zenodo.org/record/512862
The reproductive system of Campuloclinium macrocephalum and its implications for biocontrol implementation
No full textA dissertation submitted in fulfilment of the requirements for the degree of Master of Science to the Faculty of Science, University of the Witwatersrand, Johannesburg, 2022Invasive species are a threat to biodiversity therefore it is imperative to determine the factors that facilitate the invasion potential of a species. Campuloclinium macrocephalum Less. (DC), the ‘pompom weed’, is an alien invasive species in South Africa and is currently threatening the persistence of the grassland, wetland, and savanna biomes. The species is also significantly contributing to a decline in plant diversity by outcompeting native vegetation in these areas. Various integrated approaches using combinations of chemical, mechanical and biocontrol management programs have been developed to manage the spread of the species in its invaded range, however the species has still been able to persist.
The persistence of the species was hypothesised to be a consequence of the co-occurrence of apomixis and polyploidy, however despite the identification of triploid and tetraploid cytotypes in South African populations of the pompom weed, the reproductive strategy of the species has not yet been determined. The aim of this study was therefore to infer whether populations of C. macrocephalum (pompom weed) reproduces via vector-mediated crosses, self-pollination or apomixis (either facultative or obligate) and examine the relationship of the mode of reproduction with ploidy level. Male fertility was also assessed to ascertain if interploidy gene flow was possible. The collated information was then used to infer the potential impact of reproductive strategies and polyploidy on biocontrol. All examined populations were shown to have high mean pollen viability percentages of 90% and 98% with no significant differences in pollen viability amongst the four populations. The high pollen viability percentages were supported by prolific pollen grain germination on the stigmatic surfaces (margins of style at base of style branches) and the sides of the style. This suggested that the pollen grains can fertilize and interploidy mating is likely possible in South African populations of the pompom weed. It is plausible that the high pollen viability is enabling triploids to act as a ‘triploid bridge’. However, the high pollen viability was confounded by the pollen tube analyses revealing that pollen tube growth is being arrested on the stigmatic surface suggesting that overall male fertility is low. The arrested pollen tube growth is typically associated with a ‘triploid block’. Nevertheless, the production of viable gametes can reduce the triploid block and facilitate gene flow between populations.
The predominant mode of reproduction was determined by assessing the contribution of insects to pollen transfer, pollinator exclusion experiments, germination trials, pollen tube growth to the ovules and genetic analyses. We found that the African Monarch butterfly (Danaus chrysippus) and the honeybee (Apis mellifera) contributed most to pollen transfer in comparison to the other insects visiting C. macrocephalum. A pollinator exclusion experiment showed that the pompom weed can set seed in the absence of pollinators, albeit at lower quantities than in the open treatments. Nevertheless, germination percentages showed that reproductive success was similar between open and bagged treatments in each population. The Modderfontein population showed lower reproductive success and seedling establishment in comparison to the other populations, presumably due to the severity of the biocontrol infestation on this population. Genetic analyses revealed low genetic variation within and amongst populations. Pollen tube analyses showed no pollen tube growth to the ovules in all samples, which suggests that seed set is independent of fertilization. The lack of pollen tube growth is a strong indicator of obligate autonomous apomixis which is further corroborated by the low genetic differentiation between maternal plants and their respective offspring.
The co-occurrence of apomixis and polyploidy made it difficult to discern which factor contributes more to the invasiveness of the species, however, we hypothesise that autonomous apomixis provides the pompom weed with the competitive advantage to persist in its invaded range. However, further studies on the reproductive strategies of tetraploid cytotypes are needed to confirm this hypothesis. The low genetic variation suggests that all populations should be equally susceptible to biocontrol agents, however that this may be affected by other factors such as environmental conditions or phenotypic plasticity. Phenotype plasticity refers to a single genotype producing different phenotypes in response to environmental conditions. This could reduce the efficacy of biocontrol agents as they may exhibit differential responses on different phenotypesPC(2023
Influence of polyploidy on morphology, genetic differentiation and reproductive strategy amongst varieties of Rhodohypoxis baurii (Hypoxidaceae)
No full textA research report submitted in fulfillment of the requirements for the degree Master of Science (MSc) in Animal, Plant and Environmental Sciences in the Faculty of Science, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa 2023Evolutionary mechanisms, such polyploidy (increase in chromosome sets), alters plant morphology, gene flow and reproductive strategies, which can facilitate the generation or loss of species. Rhodohypoxis L. (Hypoxidaceae) is a small near-endemic Drakensberg genus comprising six species, one of which is Rhodohypoxis baurii. Rhodohypoxis baurii contains three morphologically distinct varieties, with varying ploidy-levels: R. baurii var. baurii (2×, 4×), R. baurii var. platypetala (2× 3× , 4×), and R. baurii var. confecta (2×). Therefore, R. baurii is an ideal system to evaluate whether polyploidy leads to lineage divergence or homogenization and contributes to biodiversity in this lineage. The aim of the study was to assess the influence of ploidy on morphology, genetic differentiation and reproductive strategy among varieties of Rhodohypoxis baurii (Hypoxidaceae), as well as to better recognise the three varieties. Thirty vegetative, floral, and reproductive traits were measured across 124 herbarium specimens and 43 individuals housed in the greenhouse. A matrix containing 20 quantitative and 12 qualitative characters was constructed and a Principal Coordinates Analysis (PCoA) and Non-Metric Multidimensional Scaling analysis (NMDS) were conducted. Important distinguishing morphological features that had a high eigenvalue (shown via a PCA) were selected for direct comparison using box and whisker box plots to compare means ± standard errors (SE). Certain morphological traits such as anther length, peduncle length and tepal sizes differed significantly among the varieties and ploidy levels, with polyploid individuals exhibiting the gigas effect. This was especially evident in R. baurii var. platypetala, which contained many polyploid individuals and exhibited larger flowers (longer and wider tepals) and larger anthers compared to other varieties. Rhodohypoxis baurii var. confecta and R. baurii var. platypetala are genetically, geographically and morphologically similar, differing only in flower colour, flower size and peduncle length. However, most of these differences can be attributed to differences in ploidy and /or altitude with R. baurii var. confecta occurring at higher altitudes and R. baurii var. platypetala containing multiple ploidy-levels. It is therefore evident that ecological differences and polyploidy have shaped the morphological differences in these two taxa. In addition, R. baurii var. baurii populations in the 7 Eastern Cape Drakensberg were morphologically, geographically and genetically distinct from all other populations and varieties, and may be a new/ undescribed taxon; however, this warrants further investigation. Out of 231 experimental crosses, 113 intra-varietal and inter-varietal crosses produced seeds. Rhodohypoxis baurii polyploid individuals show a shift away from sexual reproduction to asexual reproduction as they all showed higher rates of clonal reproduction than the diploid individuals. Moreover, crosses between polyploids yielded lower seed sets and lower germination rates than diploid-diploid crosses. Genetic differentiation and gene flow were quantified for 280 individuals among the varieties and ploidy-levels across 11 populations using 12 microsatellite markers labelled with the FAM NED dyes. Leaf material was collected from 237 individuals of Rhodohypoxis baurii (R. baurii var. confecta n = 88, R. baurii var. baurii n = 87, R. baurii var. platypetala n = 62) and flow cytometry conducted to estimate ploidy. A latitudinal ploidy gradient was evident across sampled populations that corresponds with shifts in reproductive strategy, and changes in the extent of gene flow. Population genetic structure coincided primarily with geographic localities, with diploid Northern Drakensberg populations having similar allelic diversity to one another. The Central and Southern Drakensberg mixed ploidy populations also showed similar allelic diversity but differed from the tetraploid Eastern Cape Drakensberg populations. Furthermore, gene flow was higher between geographically close populations irrespective of ploidy-level, with geographically isolated regions (such as the Eastern Cape Drakensberg) and outlying populations (i.e. Karkloof) showing unique genotypes, indicating little gene flow and allele sharing. Consequently, shifts in reproductive strategy and geographic isolation are likely changing gene flow patterns among varieties and ploidy levels which appears to be facilitating both lineage diversification and homogenization in this speciesMM202
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Cineraria L. (Senecioneae, Asteraceae) - its taxonomy, phylogeny, phytogeography and conservation
No full textStudent no:7719196
PhD thesis 2005
Faculty of Science, School of Animal, Plant and Environmental Sciences.This study aimed to investigate the phylogeny of Cineraria L. to elucidate its position in
the tribe Senecioneae (Asteraceae), to delimit its generic and species boundaries, explore
species relationships (infrageneric structure) and produce a monograph of the genus. It also
aimed to examine its distribution, phytogeographic affinities, levels of rarity and endemism
in Cineraria, to identify some of the factors contributing to rarity in Cineraria and to
highlight implications for conservation.
Phylogenetic analyses were performed using morphological and molecular (DNA sequence)
characters to elucidate relationships within the genus and between Cineraria and selected
related genera in the subtribe Senecioninae. The phylogenetic species concept was applied
- suites of diagnostic characters were used to characterise species. The phenetic approach,
using Cluster Analysis and Principal Coordinates Analysis, was applied to investigate
variation in two highly variable species, C. deltoidea Sond. and C. lobata L’Hér. Species
distributions were mapped and the number of species per degree square was plotted for
southern Africa to identify centres of diversity and endemism. Rare species were identified
and categorised according to Rabinowitz’s criteria of geographic range, habitat specificity
and local population size.
Cineraria now has a more homogenous generic concept, characterised as herbs or
subshrubs with palmately veined leaves, radiate, calyculate capitula, penicillate style apices
and obovate, compressed cypselae with two distinct margins or wings and a substantial
carpopodium. Eleven species have been removed from the genus and two new genera,
Bolandia Cron and Oresbia Cron & B.Nord. have been established to accommodate three
of the species. Two species have been reassigned to and another reinstated in Senecio L.
The affinities of five species remain unresolved.
Cineraria now comprises 35 species with four new subspecies and two new varieties
recognised. Eight species have been placed in synonymy and five new species have been
described during this revision. The status of C. deltoidea as a single, highly variable
species, widespread throughout the eastern mountains of Africa, has been confirmed.
Cineraria lobata has been shown to be a very variable species and the geographic and
morphological variation has been formally (and informally) recognised. No infrageneric
classification has been applied to Cineraria as a robust phylogeny of all the species has yet
to be hypothesised.
A southern African origin for Cineraria in the Western and/or Eastern Cape is postulated,
based on the current distribution of the sister genus Bolandia and Cineraria mollis DC.
iv
Cineraria appears to have undergone rapid speciation fairly recently, as indicated by the
lack of variation in the molecular data analysed, with reticulate evolution playing an
important role in its evolutionary history (as seen by the lack of congruence between the
chloroplast and nuclear DNA sequences).
The centre of diversity of Cineraria is the KwaZulu-Natal Midlands, part of the
Maputaland-Pondoland Centre of endemism in southern Africa. Cineraria has an
afromontane affinity, and fifteen species endemic to specific mountains or regions of
endemism and five near-endemics have been identified in Cineraria. Eleven species have
been shown to be rare (in the sense of low abundance, restricted range and high habitat
specificity), however only five are considered to be threatened as indicated by IUCN Red
Data Criteria. However, at least seven species are Data Deficient and require further
investigation. Causes of rarity in Cineraria are linked to narrow habitat specificity,
particularly soil or rock type and/or altitudinal range
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