1,720,976 research outputs found
Patterns of species richness in two African-centered, aridity-adapted flightless weevil lineages (Coleoptera: Curculionoidea)
No full textRamdhani, Syd (2017): Patterns of species richness in two African-centered, aridity-adapted flightless weevil lineages (Coleoptera: Curculionoidea). Zootaxa 4323 (4): 593-599, DOI: https://doi.org/10.11646/zootaxa.4323.4.1
FIG. 1 in Analysis of the diversity and distributional patterns of coleopteran families on a global scale
No full textFIG. 1. Global patterns of coleopteran family diversity and endemism. (a) family richness; (b) weighted endemism.Published as part of Moodley, Sandrini, Procheş, Şerban, Perera, Sandun J., Lubbe, Edrich, Ramdhani, Syd & Leschen, Richard A. B., 2022, Analysis of the diversity and distributional patterns of coleopteran families on a global scale, pp. 575-583 in Zootaxa 5138 (5) on page 577, DOI: 10.11646/zootaxa.5138.5.5, http://zenodo.org/record/657192
FIG. 2 in Analysis of the diversity and distributional patterns of coleopteran families on a global scale
No full textFIG. 2. Cluster analyses and corresponding regionalisation schemata based on (a) a streamlined but nevertheless fairly comprehensive dataset excluding very widespread families and family-poor ecoregions; (b) endemic-rich ecoregions only.Published as part of Moodley, Sandrini, Procheş, Şerban, Perera, Sandun J., Lubbe, Edrich, Ramdhani, Syd & Leschen, Richard A. B., 2022, Analysis of the diversity and distributional patterns of coleopteran families on a global scale, pp. 575-583 in Zootaxa 5138 (5) on page 578, DOI: 10.11646/zootaxa.5138.5.5, http://zenodo.org/record/657192
Taxonomic revision of the Memecylon natalense species-complex in southern Africa.
Full text linkMasters Degree. University of KwaZulu-Natal, Durban.iv
ABSTRACT
Two Memecylon species (M. natalense and M. bachmannii) were previously recognized in southern Africa, and three species of M. section Buxifolia as occurring in Mozambique (M. natalense, M. torrei and M. insulare). However, a recent nrDNA phylogeny revealed that M. natalense as previously circumscribed is not a monophyletic group and includes some geographically outlying populations warranting recognition as distinct evolutionary lineages. In this dissertation, I present the results of a comprehensive morphological study and revision of the ‘M. natalense species-complex’ including the following taxa: M. natalense sensu stricto (endemic to South Africa in KwaZulu-Natal, Eastern Cape, Mpumalanga and Limpopo), M. incisilobum (southern Mozambique), M. nubigenum (southern Malawi), M. rovumense (southeastern Tanzania), M. aenigmaticum (northern Mozambique), M. sp. nov. 1 (northeastern Kwazulu-Natal, South Africa), M. sp. nov. 2 (Eastern Cape province, South Africa), and M. sp. nov. 3 (Limpopo province, South Africa). Although M. bachmannii (Eastern Cape and KwaZulu-Natal) is morphologically distinct, it was also included in the present study because of recent nrDNA work indicating a close relationship with M. natalense. Species boundaries were investigated using phenetic and cladistic methods based on morphology. Phenetic analysis using the Unweighted Pair Group Method with Arithmetic Mean (UPGMA) revealed that M. bachmannii clustered independently, M. sp. nov. 1 clustered close to M. incisilobum, M. aenigmaticum clustered close to M. rovumense, and M. nubigenum clustered close to a subcluster consisting of M. natalense, M. sp. nov. 2 and M. sp. nov. 3. The morphological cladistic results were congruent with a previous molecular analysis in that M. sect. Buxifolia was monophyletic. Memecylon rovumense + M. aenigmaticum and M. incisilobum + M. sp. nov. 1 appeared in separate clades. Memecylon bachmannii and M. nubigenum were each monophyletic, while M. natalense, M. sp. nov. 2 and M. sp. nov. 3 appeared in an unresolved polytomy. Overall, the cladistic results were in agreement with the UPGMA analysis but were less resolved. Vegetative and fruit morphology have proven to be of great diagnostic value in delimiting the members of the M. natalense species-complex. Four new species have been named and described, while a further three new species are proposed. Dichotomous keys are provided, and the conservation status of each species is assessed according to the criteria of the IUCN. A lectotype should be designated for M. natalense. With these additions, the flora of Mozambique now has seven species of Memecylon (including six species in M. sect. Buxifolia). In South Africa, the number of recognized Memecylon species has increased from two to five
The role of remote sensing in invasive alien plant species detection and the assessment of removal programs in two selected reserves in the eThekwini Municipality, KwaZulu-Natal Province.
Full text linkDoctor of Philosophy in Environmental Sciences. University of KwaZulu-Natal, Durban 2016.One of the major current concerns by conservationists is alien invasive plants due to their rapid spread and threat to biodiversity. The detection of Invasive Alien Plant Species (IAPs) can aid in monitoring and managing their invasion on ecosystems. In South Africa approximately 10 million hectares of land have been invaded. To combat this invasion, the Working for Water program was initiated in 1995 aimed at manually removing them. Multispectral imagery can facilitate identification, assess removal initiatives and improve efficiency of IAP removal. The aim of this study is to determine the most appropriate sensor to detect three IAPs (Acacia podalyriifolia, Chromolaena odorata and Litsea glutinosa) and assess clearing programs of these species in two protected areas (Paradise Valley and Roosfontein Nature Reserves) within the eThekwini municipality, in KwaZulu-Natal province, South Africa using remote sensing. The three satellite sensors examined in this study included Landsat 7 ETM+, SPOT 5 and WorldView-2. The study also assessed four image classifiers (Parallelepiped, Maximum Likelihood, Spectral Angle Mapper and Iterative Self Organising Data Analysis Technique) in the detection of the selected IAPs. These sensors and techniques were compared based on their level of accuracy at detecting selected IAPs. The results of the study showed that WorldView-2 imagery and the Maximum Likelihood classifier had the highest overall accuracy (66.67%) , resulting in the successful classification of two (Acacia podalyriifolia and Chromolaena odorata) out of the three target species. This is due to the high spatial resolution of WorldView-2 imagery. This combination was then used to asses clearing of the selected IAPs by examining species distribution and density before and after clearing. Here the overall accuracies for the Paradise Valley and Roosfontein Nature Reserves were successful with accuracies above 85%. The density and distribution of all three IAPs decreased substantially in both sites except for the L. glutinosa species located in the Paradise Valley Nature Reserve which showed no significant decrease. These results show that geospatial data (especially remote sensing data) can be successfully used in both the detection of IAPs and the assessment of their removal
Towards understanding alien floristics within an urban matrix: the case of Durban, South Africa.
No full textDoctoral Degree. University of KwaZulu-Natal, Durban.Invasive alien plant species (IAPs) represent a major threat to biodiversity loss and ecosystem functioning globally. Alien species can take advantage of changes in ecosystems brought about by natural and non-natural disturbances and compete with indigenous species for resources. Urban areas are becoming increasingly susceptible to plant invasions due to increasing anthropogenic activity levels as urban human populations increase and changing climatic conditions that favour alien species. If uncontrolled, IAP impacts can bring about the transformation of natural habitats and exclusion of indigenous species. Given the limited financial and human resources available for IAP monitoring and control in developing countries like South Africa, increased efforts to monitor the prevalence of IAPs more efficiently and identify the drivers of invasiveness within cities is urgently needed to prioritise urban green spaces and species for monitoring and control interventions. Frameworks to monitor alien invasions, identify their drivers and impacts and prioritise sites and species for control of alien plants have been limited in the urban context, particularly within developing countries such as South Africa. Where these frameworks have been developed, there are challenges of them not being equally effective at different geographic scales and across different habitats. Furthermore, these frameworks often also suffer the weakness of not capturing the multi-dimensionality of plant invasiveness. This inspired the current study, which aimed to inform the design of an evidence-based framework that aids in prioritising urban green spaces and alien species for monitoring and control interventions by carrying out a set of inter-related investigations that addressed the following research questions: (1) What are the major environmental drivers of alien species (particularly IAPs) distribution? (2) Are alien and indigenous plant functional diversity (FD) and alien-indigenous co-occurrence patterns influenced by non-natural disturbance? (3) What is the influence of non-natural disturbance on the alien and indigenous soil seed bank (SB) floristics? and (4) Can selected seed physical and/or chemical traits be used as potential indicators of IAP persistence in natural SBs? These research questions were addressed using a case study approach: plants occurring within selected natural green spaces in an urban matrix in the rapidly developing city of Durban (eThekwini Metropolitan Area [EMA]), located within the Maputaland-Pondoland-Albany biodiversity hotspot in subtropical KwaZulu-Natal, South Africa. Classical vegetation survey techniques were used to identify and quantify (in terms of richness, density and diversity) aliens within 30 natural green spaces in the study area. Levels of non-natural disturbance were quantified using a scoring matrix, and soil SB samples were collected from each site. Cumulatively, 80 alien plant species were identified, of which 35 are presently categorised as IAPs in the EMA. Once it was established that IAP species richness and density were significantly positively related to disturbance level, selected parameters measured (viz. alien species richness and density) were used to develop an Alien Invasive Index (AII), the utility of which was validated in terms of its ability to discriminate between sites with low and high levels of invasiveness. The findings demonstrate the value of integrating the data generated using vegetation surveys and Geographic Information Systems to monitor and prioritise urban green spaces for alien control interventions. Importantly, the results suggest that the AII could assist in identifying invasive plant hotspots within urban areas. In a related study, alien and indigenous floristic patterns were probed further by comparing alien and indigenous species richness, density, diversity (alpha and functional), and species co-occurrence levels at the 30 sites in relation to non-natural disturbance levels. The ratio of alien to indigenous species was 1:1.5, with Asteraceae being the most dominant family. The relationship between species richness and alpha diversity differed for alien and indigenous species. Alien species were found to have higher FD, except for reproductive mode. Additionally, FD was significantly related to disturbance levels, alien species richness, and alien plant density. Co-occurrence data showed that alien-indigenous species pairs cooccur at high levels in urban spaces. Three notable alien-indigenous pairs (Centella asiaticaConyza sumatrensis, Centella asiatica-Solanum mauritianum and Bidens pilosa-Commelina erecta) co-occurred at more than 40% of sites, while two alien-alien pairs (Solanum mauritianum-Lantana camara and Conyza sumatrensis-Tagetes minuata) co-occurred at more than 50% of sites. The positive interactions between different alien species identified here contribute to the growing amount of evidence that supports the Invasional Meltdown Hypothesis (IMH). The results also showed that non-natural disturbance might lead to high levels of alien plant species diversity and facilitatory alien-alien and alien-indigenous species interactions. Understanding co-occurrence patterns could help design alien control programmes that focus on reducing alien-alien facilitation. For the study examining alien and indigenous species soil SBs in relation to nonnatural disturbance across the 30 sites, samples collected were processed using a modified seedling emergence method, incubated under greenhouse conditions (with irrigation), and monitored for one year. Germinants were identified and quantified, and comparisons were made between the soil SB and standing vegetation (SV). Cumulatively, 70 species belonging to 20 families were identified within the SB, with a higher presence of indigenous (60%) than alien species (40%). Overall, the SB flora was dominated by graminoids. Of the 70 species found in the SB, 69 were shared with the SV. Irrespective of the disturbance level, indigenous was higher than alien plant density within the SB. The findings of this study have implications for managers of urban green spaces since alien species in SBs could exploit niches created by disturbances, promoting urban invasions. In the final investigation, seeds of five IAPs were buried for two years at an experimental site to mimic seed burial within natural SBs. Additionally, the seeds of these species were characterised in terms of selected morphological and anatomical (seed mass, seed size, seed coat thickness) and chemical traits (estimated lipid content and changes in lipid melting properties). This study was designed to assess whether seed physical and/or chemical traits can be used as potential indicators of IAP persistence in natural SBs. Batches of buried seeds were exhumed every three/six months for viability (germinated seeds + seeds that stained positively following a Tetrazolium Chloride Test). Seed mass, size and coat thickness differed significantly across species, with Canna indica having the biggest and heaviest seeds of all species and the thickest seed coat. Solanum mauritianum had the smallest and lightest seed, with one of the thinnest seed coats. Results showed decreases in viability for four species (Canna indica, Melia azedarach, Senna didymobotrya, and Ricinus communis), while Solanum mauritianum maintained a 100% viability throughout the experimental period. However, while the viability of C. indica, R. communis, and S. didymobotrya was dominated by germinable seeds before burial, as viability declined with an increase in burial time, viability was dominated by seeds that were not germinable but stained positively. Melia azedarach differed slightly, where viability declined with burial time, but the majority of the seeds that were viable remained germinable. The longest ageing rate based on P50 was observed for C. indica (lowest estimated lipid content), while M. azedarach had the shortest ageing rate (highest estimated lipid content). Decreases in germination over time for C. indica, R. communis, M. azedarach, and S. didymobotrya led to changes in either/both enthalpy of melting of the lipid, and the temperature of the lipid melt, which could be related to different seed deterioration mechanisms when buried. This study did not identify significant relationships between the seed physical and/or chemical traits and SB longevity using the traits investigated. This could be explained by the relatively low number of species and traits studied and/or the phenotypic plasticity associated with seed post-harvest physiology in wild species. Nevertheless, the study gave rise to the beginnings of a conceptual continuum of IAP seed bank longevity, which, once populated with data for more species, could supplement the criteria currently used for assessing species invasiveness. As mentioned earlier, alien plant invasions are a major challenge for developing countries, particularly in urban settings. In countries like South Africa, the management of IAPs is complicated by heterogeneous combinations of non-natural disturbances, site-specific levels of disturbance intensity, and diverse vegetation types and associated species richness. The results clearly show that IAPs thrive under high levels of non-natural disturbance in urban green spaces and that alien and indigenous species can co-occur in various vegetation types. The AII was able to identify alien hotspots within the study area and may represent a useful tool for conservation practitioners/land managers. Lantana camara and Solanum mauritianum emerged as the most problematic IAPs currently in the study area. It was also evident that disturbance levels play a role in soil SBs of alien and indigenous species richness and plant density, and some problematic IAPs, notably S. mauritianum, can persist in SBs for long periods due to morphological, anatomical, and chemical traits. The results generated were used to design a multi-disciplinary and multi-dimensional framework that aids in prioritising sites and species for alien plant monitoring and control within urban areas. The methods proposed for assessing the prevalence and drivers of alien plant species and the indicators identified as potential indicators of their impacts in the framework can assist land managers, practitioners, and researchers develop recommendations and actions for alien plant monitoring and control in urban areas. The framework is designed to supplement and aid, and not replace, existing EMA policies/guidelines for alien plant control by preceding their planning and preparation phases. It could also help in developing new approaches to monitoring alien plant species in urban spaces
Scotch broom (cytisus scoparius (L.) link) and gorse (ulex europaeus L.) in South Africa: an assessment of invasiveness, management options and feasibility for countrywide eradication.
Full text linkMaster of Science in Life Sciences. University of KwaZulu-Natal, Durban 2016.Abstract available in PDF file
The use of open top chambers to assess the effects of elevated temperatures on subtropical grassland vegetation in situ : a case study on KwaZulu-Natal sandstone sourveld.
Full text linkMaster of Science in Biological and Conservation Sciences. University of KwaZulu-Natal, Durban 2016.Abstract available in PDF file
The relationship between the length of flowering periods and the distribution ranges of plant species in eastern South Africa.
Full text linkThesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2012.Flowering is one of the most important stages in determining the successful survival and
spread in plants. The duration of the flowering period is closely associated with successful
reproduction, making it essential to understand the importance and effects of the length of
flowering on various macroecological variables across plant species. The effects of the length
of flowering periods on the distribution range size of species have seldom been investigated.
This project aims to identify any macroecological relationship that may exist between the
length of flowering periods and the distribution ranges of plant species endemic to the eastern
part of South Africa, a region well known for its floral diversity. Range size and flowering
phenology data were collected for several genera that are centred in the region (Cussonia,
Gymnosporia, Searsia, Streptocarpus, Pavetta, Plectranthus, Crinum, Eulophia, Gladiolus,
Kniphofia, Satyrium, Watsonia and Zantedeschia). At genus level, the relationship varied
considerably. While significant correlations between the two variables were retrieved in four
genera, the meaning of these patterns differed. In some cases, these suggested that a larger
range was achieved through successful pollination due to extended flowering periods,
whereas in others, it is probably just an effect of different flowering seasons in different areas
where the range is large enough to comprise diverse climates. When incorporating variables
such as growth form (narrowly and broadly-defined) and genus identity in analyses of covariance
between flowering durations and various measures of distribution, the association of
genera was far greater than that of growth form. It can be concluded that both range size and
the length of the flowering season are the result of numerous factors acting jointly, which
differ across plant groups and are likely to be susceptible to changes in climate and biological
invasions. This means that the relationship between range size and flowering period is driven
by different factors in different genera, suggesting that the conservation of plant diversity in
the face of global change will have to consider the complexity of flowering patterns, and it is
likely that lineage-specific approaches for different plant groups will be necessary
A biogeographic study of the KwaZulu-Natal sandstone sourveld patches within the eThekwini Municipal Area.
Full text linkMaster of Science in Ecology. University of KwaZulu-Natal, Durban 2016.KwaZulu-Natal Sandstone Sourveld (KZNSS) is an endangered vegetation type in South Africa. Approximately 68% of KZNSS is transformed, with remaining patches existing within an urban and suburban matrix. Fragmented patches of KZNSS found within the eThekwini Municipal Area (EMA) represent a conservation priority but are often not managed/ conserved appropriately as they are sometimes misclassified as Indian Ocean Coastal Grassland Belt (IOCGB) based on their close proximity to the latter vegetation type in a number of areas. This motivated the present study which involved characterising the flora of eight grassland patches within the EMA presently categorised as follows: three KZNSS sites (viz. Giba Gorge Environmental Precinct, Inanda Mountain and Springside Nature Reserve), three IOCBG sites (viz. Spyhill Open Space, Tanglewood Nature Reserve and Edgecliff Open Space) which are currently called Ecotonal given their close proximity to KZNSS, and two IOCGB sites (viz. New Germany Nature Reserve and Roosfontein Nature Reserve).
Floristic surveys, which involved quadrats sampling were performed year round (c. 60% in the winter, 30% in the summer and the remaining quadrats performed in spring or autumn) until an 80% sampling effort was achieved. Additionally, transect sampling was performed monthly for a year at each site. Data from both methods were used to determine the vegetation composition and structure at each site. The below-ground flora of each site was also characterized by removing 30 – 35 soil samples after the two main flowering events (late November and early December as well as late April and early May) at each site and allowing germination to occur, with the resulting germinants being identified and quantified. Field observations on levels of disturbance and management practices at each were also considered.
When data for quadrats and transects were pooled, 263 species were found to occur across the eight sites, with 110 of these being common to all three vegetation categories. Only one of the eleven endemic taxa characteristic of KZNSS were found across all three vegetation categories, while none of the endemic taxa associated with IOCBG were found, suggesting
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that identifying KZNSS or IOCBG based on endemic (i.e. diagnostic) species may be inappropriate at the sites investigated here. Further comparisons showed KZNSS and Ecotonal to contain more species than IOCBG, which were spread across more plant families (55 found in total), although IOCBG had one less site than KZNSS and Ecotonal. Diversity measures indicated that Ecotonal is more similar to KZNSS, with more species in common between KZNSS and Ecotonal than Ecotonal had with IOCBG. Additionally, diversity measures show very little differentiation between the dominant taxa of IOCBG from KZNSS. Cluster analyses and ordinations confirmed the current classification of Ecotonal sites as part of IOCBG, despite Ecotonal sharing more superficial similarities with KZNSS. Island biogeography theory‟s area and distance effects were not upheld – most likely due to the sites not being truly isolated from each other and a very localised spatial scale, the limited temporal scale (current status a result of the past 200 years), the lack of a true originating mainland and anthropogenic disturbance.
Interestingly, the below-ground flora represented only c. 10% of the species found above-ground for all three categories, with Sørenson similarity index ranging from c. 15 – 22% as opposed to the 50% expected for southern African grasslands. This suggests that seedbank health and hence, regenerative potential may be poor at many of these sites and this may necessitate species reintroduction and habitat restoration at a number of these sites. Additionally, the effects of disturbance were evident across sites in all three vegetation categories, with disturbed sites (Edgecliff Open Space, Inanda Mountain and Roosfontein Nature Reserve) containing fewer species of conservation concern, fewer indigenous taxa in general and more alien plant taxa. Diversity indices also suggest that disturbed sites were more heterogeneous. However, disturbance agents such as herbivory appear to have had an enriching effect in term of the abundance of graminoids within the germinable soil seedbank. Alien taxa also occurred frequently in the below-ground flora but were not noted in the above-ground flora which suggests that given further disturbance/transformation, some of these sites are prone to alien plant invasion. The study suggests that IBT is not applicable to vegetation islands (grasslands in this case) with varying levels of transformation in urban matrices. The results confirm the high levels of transformation reported for sub-tropical grasslands within South Africa, specifically KZNSS, and highlight the need for floristic surveys to delimit different grassland types and in turn ensure their appropriate conservation and/or rehabilitation
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