Using molecules and morphology to infer the phylogenetic relationships and evolutionary history of the Dirini (Nymphalidae: Satyrinae), a tribe of butterflies endemic to Southern Africa
- Price, Benjamin W, Villet, Martin H, Walton, Shaun M, Barker, Nigel P
- Authors: Price, Benjamin W , Villet, Martin H , Walton, Shaun M , Barker, Nigel P
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442397 , vital:73981 , https://doi.org/10.1111/j.1365-3113.2010.00560.x
- Description: The first empirically supported phylogenetic hypothesis of relationships for the southern African endemic butterfly tribe Dirini is presented. Data derived from the morphology and ecology of the adults and immature stages (33 characters), and portions of the mitochondrial gene cytochrome oxidase I (COI) and the nuclear genes elongation factor 1α (EF1α) and wingless (WG) (totalling 1734 bp) were used to infer the relationships of the in‐group genera. An expanded molecular dataset using four genera from the Nymphalini and Satyrini to root the tree, and three genera from the Melanitini to test the monophyly of the tribe, was analysed using parsimony and Bayesian methods. Estimates of divergence times were calculated using two fossil calibrations under a relaxed molecular clock model. The monophyly of the tribe and each in‐group genus were strongly supported. Key findings are the sister‐taxon relationship of Aeropetes and Tarsocera, the apparent simultaneous or nearly simultaneous radiation of four lineages, the polyphyly of the species within Torynesis, and the apparent trans‐Atlantic dispersal of the ancestors of Manataria about 40 Ma. Estimates of divergence times indicate that the tribe has undergone two major radiations since its origin: the first when they left forest habitats in the mid–late Oligocene, shortly after the radiation of the grasses (Poaceae), and the second in the early‐middle Pliocene, coinciding with the aridification of southern Africa and the spread of conditions that favoured C4 grasses over the C3 grasses that dirine larvae prefer to eat. The high species diversity within the tribe appears to be partly a taxonomic artefact that may have resulted from the misinterpretation of climate-related phenotypic variation within extant species. Relocation and breeding experiments should test this hypothesis.
- Full Text:
- Authors: Price, Benjamin W , Villet, Martin H , Walton, Shaun M , Barker, Nigel P
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442397 , vital:73981 , https://doi.org/10.1111/j.1365-3113.2010.00560.x
- Description: The first empirically supported phylogenetic hypothesis of relationships for the southern African endemic butterfly tribe Dirini is presented. Data derived from the morphology and ecology of the adults and immature stages (33 characters), and portions of the mitochondrial gene cytochrome oxidase I (COI) and the nuclear genes elongation factor 1α (EF1α) and wingless (WG) (totalling 1734 bp) were used to infer the relationships of the in‐group genera. An expanded molecular dataset using four genera from the Nymphalini and Satyrini to root the tree, and three genera from the Melanitini to test the monophyly of the tribe, was analysed using parsimony and Bayesian methods. Estimates of divergence times were calculated using two fossil calibrations under a relaxed molecular clock model. The monophyly of the tribe and each in‐group genus were strongly supported. Key findings are the sister‐taxon relationship of Aeropetes and Tarsocera, the apparent simultaneous or nearly simultaneous radiation of four lineages, the polyphyly of the species within Torynesis, and the apparent trans‐Atlantic dispersal of the ancestors of Manataria about 40 Ma. Estimates of divergence times indicate that the tribe has undergone two major radiations since its origin: the first when they left forest habitats in the mid–late Oligocene, shortly after the radiation of the grasses (Poaceae), and the second in the early‐middle Pliocene, coinciding with the aridification of southern Africa and the spread of conditions that favoured C4 grasses over the C3 grasses that dirine larvae prefer to eat. The high species diversity within the tribe appears to be partly a taxonomic artefact that may have resulted from the misinterpretation of climate-related phenotypic variation within extant species. Relocation and breeding experiments should test this hypothesis.
- Full Text:
Assessment of the monkfish Lophius vomerinus resource off Namibia
- Maartens, Lima, Booth, Anthony J
- Authors: Maartens, Lima , Booth, Anthony J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123863 , vital:35509 , https://doi.10.2989/025776101784528926
- Description: Monkfish (Lophius vomerinus and L. vaillanti) constitute a commercially important resource off Namibia. During 1998, the Lophius resource was the fourth most important commercial resource in terms of landed mass (c. 17 000 tons) and the fifth most important commercial resource in terms of export value (U$19.8 million) of the Namibian fishing sector (Ministry of Fisheries and Marine Resources, Namibia, unpublished data). Historically, monkfish constituted an important bycatch in the trawl fishery directed at hake (Merluccius spp.), but due to increasing market demand since the early 1990s, a fishery directed at monkfish and sole (Austroglossus microlepis) has developed. The Namibian Ministry of Fisheries and Marine Resources has identified the need to develop a management plan to ensure the resource’s medium and longterm sustainability (Maartens et al. 1999). Long-term resource management plans include the identification of an assessment model to represent reality so that the implications of managing the resource in future under a range of assumptions about its present status and its future dynamics (Cochrane et al. 1998) can be examined. The aim of this study was, therefore, to assess the status of at least part of the monkfish resource using a length-based cohort assessment (Jones 1979, 1984, Sparre and Venema 1998) and an age structured production model (Punt 1994, Punt and Japp 1994, Booth and Punt 1998).
- Full Text:
- Authors: Maartens, Lima , Booth, Anthony J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123863 , vital:35509 , https://doi.10.2989/025776101784528926
- Description: Monkfish (Lophius vomerinus and L. vaillanti) constitute a commercially important resource off Namibia. During 1998, the Lophius resource was the fourth most important commercial resource in terms of landed mass (c. 17 000 tons) and the fifth most important commercial resource in terms of export value (U$19.8 million) of the Namibian fishing sector (Ministry of Fisheries and Marine Resources, Namibia, unpublished data). Historically, monkfish constituted an important bycatch in the trawl fishery directed at hake (Merluccius spp.), but due to increasing market demand since the early 1990s, a fishery directed at monkfish and sole (Austroglossus microlepis) has developed. The Namibian Ministry of Fisheries and Marine Resources has identified the need to develop a management plan to ensure the resource’s medium and longterm sustainability (Maartens et al. 1999). Long-term resource management plans include the identification of an assessment model to represent reality so that the implications of managing the resource in future under a range of assumptions about its present status and its future dynamics (Cochrane et al. 1998) can be examined. The aim of this study was, therefore, to assess the status of at least part of the monkfish resource using a length-based cohort assessment (Jones 1979, 1984, Sparre and Venema 1998) and an age structured production model (Punt 1994, Punt and Japp 1994, Booth and Punt 1998).
- Full Text:
Optimization of salbutamol sulfate dissolution from sustained release matrix formulations using an artificial neural network
- Chaibva, Faith A, Burton, Michael H, Walker, Roderick B
- Authors: Chaibva, Faith A , Burton, Michael H , Walker, Roderick B
- Date: 2010
- Subjects: Neural networks (Computer science)
- Language: English
- Type: Article
- Identifier: vital:6352 , http://hdl.handle.net/10962/d1006034
- Description: An artificial neural network was used to optimize the release of salbutamol sulfate from hydrophilic matrix formulations. Model formulations to be used for training, testing and validating the neural network were manufactured with the aid of a central composite design with varying the levels of Methocel® K100M, xanthan gum, Carbopol® 974P and Surelease® as the input factors. In vitro dissolution time profiles at six different sampling times were used as target data in training the neural network for formulation optimization. A multi layer perceptron with one hidden layer was constructed using Matlab®, and the number of nodes in the hidden layer was optimized by trial and error to develop a model with the best predictive ability. The results revealed that a neural network with nine nodes was optimal for developing and optimizing formulations. Simulations undertaken with the training data revealed that the constructed model was useable. The optimized neural network was used for optimization of formulation with desirable release characteristics and the results indicated that there was agreement between the predicted formulation and the manufactured formulation. This work illustrates the possible utility of artificial neural networks for the optimization of pharmaceutical formulations with desirable performance characteristics.
- Full Text:
- Authors: Chaibva, Faith A , Burton, Michael H , Walker, Roderick B
- Date: 2010
- Subjects: Neural networks (Computer science)
- Language: English
- Type: Article
- Identifier: vital:6352 , http://hdl.handle.net/10962/d1006034
- Description: An artificial neural network was used to optimize the release of salbutamol sulfate from hydrophilic matrix formulations. Model formulations to be used for training, testing and validating the neural network were manufactured with the aid of a central composite design with varying the levels of Methocel® K100M, xanthan gum, Carbopol® 974P and Surelease® as the input factors. In vitro dissolution time profiles at six different sampling times were used as target data in training the neural network for formulation optimization. A multi layer perceptron with one hidden layer was constructed using Matlab®, and the number of nodes in the hidden layer was optimized by trial and error to develop a model with the best predictive ability. The results revealed that a neural network with nine nodes was optimal for developing and optimizing formulations. Simulations undertaken with the training data revealed that the constructed model was useable. The optimized neural network was used for optimization of formulation with desirable release characteristics and the results indicated that there was agreement between the predicted formulation and the manufactured formulation. This work illustrates the possible utility of artificial neural networks for the optimization of pharmaceutical formulations with desirable performance characteristics.
- Full Text:
Physical and biological coupling in eddies in the lee of the South-West Indian Ridge
- Ansorge, Isabelle J, Pakhomov, Evgeny A, Kaehler, Sven, Lutjeharms, Johan R E, Durgadoo, Jonathan V
- Authors: Ansorge, Isabelle J , Pakhomov, Evgeny A , Kaehler, Sven , Lutjeharms, Johan R E , Durgadoo, Jonathan V
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6493 , http://hdl.handle.net/10962/d1004477
- Description: Eddies have some decisive functions in the dynamics of the Southern Ocean ecosystems. This is particularly true in the Indian sector of the Southern Ocean, where a region of unusually high-mesoscale variability has been observed in the vicinity of the South-West Indian Ridge. In April 2003, three eddies were studied: eddy A, a recently spawned anticyclone south of the Antarctic Polar Front (APF),; eddy B, an anticyclone north of lying between the Subantarctic Front and the APF; and eddy C, a cyclone north of the APF west of the ridge. Elevated concentrations of total Chl-a coincided with the edges of the cyclonic eddy, whereas both anticyclonic eddies A and B were characterised by low total Chl-a concentrations. Biologically, the two anticyclonic eddies A and B were distinctly different in their biogeographic origin. The zooplankton community in the larger anticyclonic eddy A was similar in composition to the Antarctic Polar Frontal Zone (APFZ) community with an addition of some Antarctic species suggesting an origin just north of the APF. In contrast, the species composition within the second anticyclonic eddy B appeared to be more typical of the transitional nature of the APFZ, comprising species of both subantarctic and subtropical origin and thus influenced by intrusions of water masses from both north and south of the Subantarctic Front. Back-tracking of these features shows that the biological composition clearly demarcates the hydrographic origin of these features.
- Full Text:
- Authors: Ansorge, Isabelle J , Pakhomov, Evgeny A , Kaehler, Sven , Lutjeharms, Johan R E , Durgadoo, Jonathan V
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6493 , http://hdl.handle.net/10962/d1004477
- Description: Eddies have some decisive functions in the dynamics of the Southern Ocean ecosystems. This is particularly true in the Indian sector of the Southern Ocean, where a region of unusually high-mesoscale variability has been observed in the vicinity of the South-West Indian Ridge. In April 2003, three eddies were studied: eddy A, a recently spawned anticyclone south of the Antarctic Polar Front (APF),; eddy B, an anticyclone north of lying between the Subantarctic Front and the APF; and eddy C, a cyclone north of the APF west of the ridge. Elevated concentrations of total Chl-a coincided with the edges of the cyclonic eddy, whereas both anticyclonic eddies A and B were characterised by low total Chl-a concentrations. Biologically, the two anticyclonic eddies A and B were distinctly different in their biogeographic origin. The zooplankton community in the larger anticyclonic eddy A was similar in composition to the Antarctic Polar Frontal Zone (APFZ) community with an addition of some Antarctic species suggesting an origin just north of the APF. In contrast, the species composition within the second anticyclonic eddy B appeared to be more typical of the transitional nature of the APFZ, comprising species of both subantarctic and subtropical origin and thus influenced by intrusions of water masses from both north and south of the Subantarctic Front. Back-tracking of these features shows that the biological composition clearly demarcates the hydrographic origin of these features.
- Full Text:
Quantifying commercial catch and effort of monkfish Lophius vomerinus and L. vaillanti off Namibia
- Maartens, Lima, Booth, Anthony J
- Authors: Maartens, Lima , Booth, Anthony J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125786 , vital:35817 , https://doi.10.2989/025776101784528999
- Description: Mark-recapture models do not distinguish how ‘‘deaths’’ accrue to marked animals in the population. If animals lose their tags, then recaptures will be fewer than expected and estimates of survival will be underestimated (Arnason and Mills, 1981; McDonald et al., 2003). Similarly, if the non-reporting rate is unknown and assumed to be negligible, as is the case in some tagging studies (e.g. Cliff et al., 1996, for white sharks Carcharodon carcharias), the probability of capture can be underestimated. The effects of both these problems, inherent in cooperative tagging programmes, lead to too few tagged fish being recovered, with a positive bias on the estimation of population size. These effects are most pronounced when capture probability is low and fewer tags are available for recapture (McDonald et al., 2003).
- Full Text:
- Authors: Maartens, Lima , Booth, Anthony J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125786 , vital:35817 , https://doi.10.2989/025776101784528999
- Description: Mark-recapture models do not distinguish how ‘‘deaths’’ accrue to marked animals in the population. If animals lose their tags, then recaptures will be fewer than expected and estimates of survival will be underestimated (Arnason and Mills, 1981; McDonald et al., 2003). Similarly, if the non-reporting rate is unknown and assumed to be negligible, as is the case in some tagging studies (e.g. Cliff et al., 1996, for white sharks Carcharodon carcharias), the probability of capture can be underestimated. The effects of both these problems, inherent in cooperative tagging programmes, lead to too few tagged fish being recovered, with a positive bias on the estimation of population size. These effects are most pronounced when capture probability is low and fewer tags are available for recapture (McDonald et al., 2003).
- Full Text:
Reproductive seasonality of southern African inshore and estuarine invertebrates–a biogeographic review
- Authors: Hodgson, Alan N
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447415 , vital:74623 , https://doi.org/10.1080/15627020.2010.11657249
- Description: A literature review reveals that reproductive seasonality of less than 1% of South Africa’s inshore marine invertebrates has been studied. Approximately 95% of studies have been on large, long-lived, gonochoristic, iteroparous species, and nearly 50% on molluscs. There is only a weak relationship between biogeographic region and timing of reproduction. Nevertheless, a relatively large proportion of west coast species studied breed in winter, whereas south coast species tend to have breeding peaks in spring/summer, although many nearly always have mature gametes and probably reproduce year-round. East coast species are mainly continuous or summer breeders. The factors that control gametogenesis and trigger spawning are largely unresolved, although temperature and food are thought to be important in many species.
- Full Text:
- Authors: Hodgson, Alan N
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447415 , vital:74623 , https://doi.org/10.1080/15627020.2010.11657249
- Description: A literature review reveals that reproductive seasonality of less than 1% of South Africa’s inshore marine invertebrates has been studied. Approximately 95% of studies have been on large, long-lived, gonochoristic, iteroparous species, and nearly 50% on molluscs. There is only a weak relationship between biogeographic region and timing of reproduction. Nevertheless, a relatively large proportion of west coast species studied breed in winter, whereas south coast species tend to have breeding peaks in spring/summer, although many nearly always have mature gametes and probably reproduce year-round. East coast species are mainly continuous or summer breeders. The factors that control gametogenesis and trigger spawning are largely unresolved, although temperature and food are thought to be important in many species.
- Full Text:
An examination of feedback on draft essays, using Halliday's definition of context:
- Authors: Quinn, Lynn
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69500 , vital:29544 , https://doi.org/10.1080/10286632.2016.1255206
- Description: An historical structural understanding underpins the research reported on in this paper. The ideas of the systemic functional linguist, Michael Halliday, are used to examine a draftingresponding-redrafting process used to develop students'. academic writing in the English Language for Academic Purposes (ELAP) course at Rhodes University. Using the Hallidayan framework, I examine how the process can help students adapt to the broader culture of the university and at a more micro level how the comments made by the respondent can help student writers to acquire the academic literacy required to write essays in the context of situation of the ELAP course. The features of field, tenor and mode and their associated textual meanings (that is, experiential meaning, interpersonal meaning and textual meaning) are used to categorise the ways in which comments made at the draft stage of the writing process can develop students' writing. As a result of my research I argue in this paper that it might be useful for writing consultants/lecturers to think of their feedback to students' writing in terms of these categories and to consider whether they have helped students to develop their writing by taking into account the features of the particular social context in which the writing takes place.
- Full Text:
- Authors: Quinn, Lynn
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69500 , vital:29544 , https://doi.org/10.1080/10286632.2016.1255206
- Description: An historical structural understanding underpins the research reported on in this paper. The ideas of the systemic functional linguist, Michael Halliday, are used to examine a draftingresponding-redrafting process used to develop students'. academic writing in the English Language for Academic Purposes (ELAP) course at Rhodes University. Using the Hallidayan framework, I examine how the process can help students adapt to the broader culture of the university and at a more micro level how the comments made by the respondent can help student writers to acquire the academic literacy required to write essays in the context of situation of the ELAP course. The features of field, tenor and mode and their associated textual meanings (that is, experiential meaning, interpersonal meaning and textual meaning) are used to categorise the ways in which comments made at the draft stage of the writing process can develop students' writing. As a result of my research I argue in this paper that it might be useful for writing consultants/lecturers to think of their feedback to students' writing in terms of these categories and to consider whether they have helped students to develop their writing by taking into account the features of the particular social context in which the writing takes place.
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An intercultural approach to implementing multilingualism at Rhodes University, South Africa
- Kaschula, Russell H, Maseko, Pamela, Dalvit, Lorenzo, Mapi, Thandeka, Nelani, Linda, Nosilela, Bulelwa, Sam, Msindisi S
- Authors: Kaschula, Russell H , Maseko, Pamela , Dalvit, Lorenzo , Mapi, Thandeka , Nelani, Linda , Nosilela, Bulelwa , Sam, Msindisi S
- Date: 2009
- Subjects: Multilingualism -- South Africa , Intercultural communication , Education, Higher -- South Africa , Language and culture -- South Africa , Language and education -- South Africa , Rhodes University
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59390 , vital:27579 , doi: 10.5842/39-0-74
- Description: The work of intercultural communication theorists such as Ting-Toomey (1999) and Gudykunst (2003) has informed curriculum design and teaching methodology of the courses developed for teaching isiXhosa for vocational purposes to second language (L2) learners. This seems to be an appropriate theoretical paradigm within multilingual South Africa, where intercultural communication is becoming a daily reality for a growing portion of the population. We make use of this theory to introduce and develop experiential understanding of multilingualism at Rhodes University in various departments and, more generally, on campus.
- Full Text:
- Authors: Kaschula, Russell H , Maseko, Pamela , Dalvit, Lorenzo , Mapi, Thandeka , Nelani, Linda , Nosilela, Bulelwa , Sam, Msindisi S
- Date: 2009
- Subjects: Multilingualism -- South Africa , Intercultural communication , Education, Higher -- South Africa , Language and culture -- South Africa , Language and education -- South Africa , Rhodes University
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59390 , vital:27579 , doi: 10.5842/39-0-74
- Description: The work of intercultural communication theorists such as Ting-Toomey (1999) and Gudykunst (2003) has informed curriculum design and teaching methodology of the courses developed for teaching isiXhosa for vocational purposes to second language (L2) learners. This seems to be an appropriate theoretical paradigm within multilingual South Africa, where intercultural communication is becoming a daily reality for a growing portion of the population. We make use of this theory to introduce and develop experiential understanding of multilingualism at Rhodes University in various departments and, more generally, on campus.
- Full Text:
Evaluating the IRI topside model for the South African region: An overview of the modelling techniques
- Sibanda, Patrick, McKinnell, Lee-Anne
- Authors: Sibanda, Patrick , McKinnell, Lee-Anne
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6810 , http://hdl.handle.net/10962/d1004303
- Description: The representation of the topside ionosphere (the region above the F2 peak) is critical because of the limited experimental data available. Over the years, a wide range of models have been developed in an effort to represent the behaviour and the shape of the electron density (Ne) profile of the topside ionosphere. Various studies have been centred around calculating the vertical scale height (VSH) and have included (a) obtaining VSH from Global Positioning System (GPS) derived total electron content (TEC), (b) calculating the VSH from ground-based ionosonde measurements, (c) using topside sounder vertical Ne profiles to obtain the VSH. One or a combination of the topside profilers (Chapman function, exponential function, sech-squared (Epstein) function, and/or parabolic function) is then used to reconstruct the topside Ne profile. The different approaches and the modelling techniques are discussed with a view to identifying the most adequate approach to apply to the South African region’s topside modelling efforts. The IRI-2001 topside model is evaluated based on how well it reproduces measured topside profiles over the South African region. This study is a first step in the process of developing a South African topside ionosphere model.
- Full Text:
- Authors: Sibanda, Patrick , McKinnell, Lee-Anne
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6810 , http://hdl.handle.net/10962/d1004303
- Description: The representation of the topside ionosphere (the region above the F2 peak) is critical because of the limited experimental data available. Over the years, a wide range of models have been developed in an effort to represent the behaviour and the shape of the electron density (Ne) profile of the topside ionosphere. Various studies have been centred around calculating the vertical scale height (VSH) and have included (a) obtaining VSH from Global Positioning System (GPS) derived total electron content (TEC), (b) calculating the VSH from ground-based ionosonde measurements, (c) using topside sounder vertical Ne profiles to obtain the VSH. One or a combination of the topside profilers (Chapman function, exponential function, sech-squared (Epstein) function, and/or parabolic function) is then used to reconstruct the topside Ne profile. The different approaches and the modelling techniques are discussed with a view to identifying the most adequate approach to apply to the South African region’s topside modelling efforts. The IRI-2001 topside model is evaluated based on how well it reproduces measured topside profiles over the South African region. This study is a first step in the process of developing a South African topside ionosphere model.
- Full Text:
Investigating the effect of Genetic Algorithms on Filter Optimisation Within Fast Packet Classifiers
- Nottingham, Alastair, Irwin, Barry V W
- Authors: Nottingham, Alastair , Irwin, Barry V W
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428674 , vital:72528 , https://www.researchgate.net/profile/Marijke-Coet-zee/publication/220803190_A_Framework_for_Web_Services_Security_Policy_Negotiation/links/0fcfd50f7d806aafc8000000/A-Framework-for-Web-Services-Security-Policy-Negotiation.pdf#page=119
- Description: Packet demultiplexing and analysis is a core concern for network secu-rity, and has hence inspired numerous optimisation attempts since their conception in early packet demultiplexing filters such as CSPF and BPF. These optimisations have generally, but not exclusively, focused on improving the speed of packet classification. Despite these im-provements however, packet filters require further optimisation in order to be effectively applied within next generation networks. One identified optimisation is that of reducing the average path length of the global filter by selecting an optimum filter permutation. Since redundant code generation does not change the order of computation, the initial filter order before filter optimisation affects the average path length of the resultant control-flow graph, thus selection of an optimum permutation of filters could provide significant performance improvements. Unfortu-nately, this problem is NP-Complete. In this paper, we consider using Genetic Algorithms to’breed’an optimum filter permutation prior to re-dundant code elimination. Specifically, we aim to evaluate the effec-tiveness of such an optimisation in reducing filter control flow graphs.
- Full Text:
Investigating the effect of Genetic Algorithms on Filter Optimisation Within Fast Packet Classifiers
- Authors: Nottingham, Alastair , Irwin, Barry V W
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428674 , vital:72528 , https://www.researchgate.net/profile/Marijke-Coet-zee/publication/220803190_A_Framework_for_Web_Services_Security_Policy_Negotiation/links/0fcfd50f7d806aafc8000000/A-Framework-for-Web-Services-Security-Policy-Negotiation.pdf#page=119
- Description: Packet demultiplexing and analysis is a core concern for network secu-rity, and has hence inspired numerous optimisation attempts since their conception in early packet demultiplexing filters such as CSPF and BPF. These optimisations have generally, but not exclusively, focused on improving the speed of packet classification. Despite these im-provements however, packet filters require further optimisation in order to be effectively applied within next generation networks. One identified optimisation is that of reducing the average path length of the global filter by selecting an optimum filter permutation. Since redundant code generation does not change the order of computation, the initial filter order before filter optimisation affects the average path length of the resultant control-flow graph, thus selection of an optimum permutation of filters could provide significant performance improvements. Unfortu-nately, this problem is NP-Complete. In this paper, we consider using Genetic Algorithms to’breed’an optimum filter permutation prior to re-dundant code elimination. Specifically, we aim to evaluate the effec-tiveness of such an optimisation in reducing filter control flow graphs.
- Full Text:
Recent progress in electrochemical oxidation of saccharides at gold and copper electrodes in alkaline solutions
- Authors: Torto, Nelson
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6599 , http://hdl.handle.net/10962/d1004348
- Description: This article reviews the progress made in the past 10 years, on electrochemical oxidation of saccharides in alkaline media for gold and copper electrodes. The mechanism and processes associated with the electrochemical oxidation of saccharides at native and surface coated electrodes continues to be of great interest. Despite the effort and various mechanisms proposed, still the need for an electrochemically active material that understands the complexity associated with saccharides continues to increase as their detection poses a challenge for bioanalytical chemistry and liquid chromatography.
- Full Text:
- Authors: Torto, Nelson
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6599 , http://hdl.handle.net/10962/d1004348
- Description: This article reviews the progress made in the past 10 years, on electrochemical oxidation of saccharides in alkaline media for gold and copper electrodes. The mechanism and processes associated with the electrochemical oxidation of saccharides at native and surface coated electrodes continues to be of great interest. Despite the effort and various mechanisms proposed, still the need for an electrochemically active material that understands the complexity associated with saccharides continues to increase as their detection poses a challenge for bioanalytical chemistry and liquid chromatography.
- Full Text:
Reform in defence of sovereignty: South Africa in the UN Security Council, 2007–2008
- Authors: Bischoff, Paul, 1954-
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/161431 , vital:40626 , https://0-doi.org.wam.seals.ac.za/10.1177/000203970904400205
- Description: After 1994, South Africa became the sine qua non of an internationalist state, willing to promote cooperation amongst a plurality of actors, believing common interests to be more important than their differences. This raised the hopes of constitutionalists, and those who believed in the expansion of a liberal democratic peace. South Africa has acted out two seemingly contradictory roles: those of a reformer and those of a conserver. By 2007–2008 she had shifted towards the latter, conservative-reformist position. Thus, South Africa's voting record at the General Assembly expressed her overriding concern to regionalise African issues and minimise the US and the West shaping political events. This brought her foreign policy into sharper relief. But while in some sense successful, it came at a price: a controversy about her surrendering her internationalism and principles on human rights for African unity and traditional sovereignty. But it also marked the arrival of South Africa in the world of international Realpolitik.
- Full Text:
- Authors: Bischoff, Paul, 1954-
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/161431 , vital:40626 , https://0-doi.org.wam.seals.ac.za/10.1177/000203970904400205
- Description: After 1994, South Africa became the sine qua non of an internationalist state, willing to promote cooperation amongst a plurality of actors, believing common interests to be more important than their differences. This raised the hopes of constitutionalists, and those who believed in the expansion of a liberal democratic peace. South Africa has acted out two seemingly contradictory roles: those of a reformer and those of a conserver. By 2007–2008 she had shifted towards the latter, conservative-reformist position. Thus, South Africa's voting record at the General Assembly expressed her overriding concern to regionalise African issues and minimise the US and the West shaping political events. This brought her foreign policy into sharper relief. But while in some sense successful, it came at a price: a controversy about her surrendering her internationalism and principles on human rights for African unity and traditional sovereignty. But it also marked the arrival of South Africa in the world of international Realpolitik.
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A preliminary survey of the estuaries on the south coast of South Africa, Cape St Blaize, Mossel Bay - Robberg Peninsula, Plettenberg Bay, with particular reference to the fish fauna
- James, Nicola C, Harrison, T D
- Authors: James, Nicola C , Harrison, T D
- Date: 2008
- Language: English
- Type: text , Article
- Identifier: vital:7141 , http://hdl.handle.net/10962/d1011834
- Description: The coastal river systems on the south coast of South Africa from Cape St Blaize to Robberg Peninsula were surveyed during October and November 1994. The ichthyofaunal and physico-chemical characteristics of each system are presented and their suitability as estuarine nursery areas is discussed. Five systems (Rooi, Meul, Grooteiland, Kranshoek and Crooks) are outlets of small coastal streams and probably provide little or no habitat for either resident estuarine or migrant marine fishes owing to their small size. Four systems (Maalgate, Gwaing, Skaapkop and Kaaimans) are located within deeply incised valleys and have a permanent connection with the sea. The amount of marginal and intertidal habitat available to fishes, however, is limited due to their morphology. Six systems (Hartenbos, Groot Brak, Touw, Swartvlei, Goukamma and Noetsie) are intermittently open to the sea. Although the Touw and Swartvlei are connected to coastal lake systems, flow within these estuaries is not sufficient to prevent the build up of a sand barrier at the mouth. The Hartenbos, Groot Brak, Goukamma, and Noetsie are also periodically closed by a sand bar. The construction of a dam in the lower catchment of the Groot Brak has affected the hydrology of the system. The two remaining estuaries (Klein Brak and Knysna) are permanently open. In addition to strong tidal currents, the fixing of the mouth of the Knysna Estuary between rocky headlands also serves to maintain a permanent connection with the sea. Mugilidae and Sparidae were represented by the greatest number of species, and also dominated catches numerically and by mass. The fish fauna of all the estuaries surveyed were dominated by the juveniles of estuarine-dependent marine species and estuarine-resident species were also well represented in catches. The estuaries surveyed provide a vital habitat for both marine migrant species and resident species, most of which are endemic to the region.
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- Authors: James, Nicola C , Harrison, T D
- Date: 2008
- Language: English
- Type: text , Article
- Identifier: vital:7141 , http://hdl.handle.net/10962/d1011834
- Description: The coastal river systems on the south coast of South Africa from Cape St Blaize to Robberg Peninsula were surveyed during October and November 1994. The ichthyofaunal and physico-chemical characteristics of each system are presented and their suitability as estuarine nursery areas is discussed. Five systems (Rooi, Meul, Grooteiland, Kranshoek and Crooks) are outlets of small coastal streams and probably provide little or no habitat for either resident estuarine or migrant marine fishes owing to their small size. Four systems (Maalgate, Gwaing, Skaapkop and Kaaimans) are located within deeply incised valleys and have a permanent connection with the sea. The amount of marginal and intertidal habitat available to fishes, however, is limited due to their morphology. Six systems (Hartenbos, Groot Brak, Touw, Swartvlei, Goukamma and Noetsie) are intermittently open to the sea. Although the Touw and Swartvlei are connected to coastal lake systems, flow within these estuaries is not sufficient to prevent the build up of a sand barrier at the mouth. The Hartenbos, Groot Brak, Goukamma, and Noetsie are also periodically closed by a sand bar. The construction of a dam in the lower catchment of the Groot Brak has affected the hydrology of the system. The two remaining estuaries (Klein Brak and Knysna) are permanently open. In addition to strong tidal currents, the fixing of the mouth of the Knysna Estuary between rocky headlands also serves to maintain a permanent connection with the sea. Mugilidae and Sparidae were represented by the greatest number of species, and also dominated catches numerically and by mass. The fish fauna of all the estuaries surveyed were dominated by the juveniles of estuarine-dependent marine species and estuarine-resident species were also well represented in catches. The estuaries surveyed provide a vital habitat for both marine migrant species and resident species, most of which are endemic to the region.
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Global diversity of mayflies (Ephemeroptera, Insecta) in freshwater
- Barber-James, Helen M, Gattolliat, J-L, Sartori, Michel, Hubbard, Michael D
- Authors: Barber-James, Helen M , Gattolliat, J-L , Sartori, Michel , Hubbard, Michael D
- Date: 2008
- Language: English
- Type: text , Article
- Identifier: vital:6895 , http://hdl.handle.net/10962/d1011655
- Description: The extant global Ephemeroptera fauna is represented by over 3,000 described species in 42 families and more than 400 genera. The highest generic diversity occurs in the Neotropics, with a correspondingly high species diversity, while the Palaearctic has the lowest generic diversity, but a high species diversity. Such distribution patterns may relate to how long evolutionary processes have been carrying on in isolation in a bioregion. Over an extended period, there may be extinction of species, but evolution of more genera. Dramatic extinction events such as the K-T mass extinction have affected current mayfly diversity and distribution. Climatic history plays an important role in the rate of speciation in an area, with regions which have been climatically stable over long periods having fewer species per genus, when compared to regions subjected to climatic stresses, such as glaciation. A total of 13 families are endemic to specific bioregions, with eight among them being monospecific. Most of these have restricted distributions which may be the result of them being the relict of a previously more diverse, but presently almost completely extinct family, or may be the consequence of vicariance events, resulting from evolution due to long-term isolation.
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- Authors: Barber-James, Helen M , Gattolliat, J-L , Sartori, Michel , Hubbard, Michael D
- Date: 2008
- Language: English
- Type: text , Article
- Identifier: vital:6895 , http://hdl.handle.net/10962/d1011655
- Description: The extant global Ephemeroptera fauna is represented by over 3,000 described species in 42 families and more than 400 genera. The highest generic diversity occurs in the Neotropics, with a correspondingly high species diversity, while the Palaearctic has the lowest generic diversity, but a high species diversity. Such distribution patterns may relate to how long evolutionary processes have been carrying on in isolation in a bioregion. Over an extended period, there may be extinction of species, but evolution of more genera. Dramatic extinction events such as the K-T mass extinction have affected current mayfly diversity and distribution. Climatic history plays an important role in the rate of speciation in an area, with regions which have been climatically stable over long periods having fewer species per genus, when compared to regions subjected to climatic stresses, such as glaciation. A total of 13 families are endemic to specific bioregions, with eight among them being monospecific. Most of these have restricted distributions which may be the result of them being the relict of a previously more diverse, but presently almost completely extinct family, or may be the consequence of vicariance events, resulting from evolution due to long-term isolation.
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Impediments to the delivery of socioeconomic rights in South Africa
- Authors: Roodt, Monty J
- Date: 2008
- Language: English
- Type: Conference paper
- Identifier: vital:6318 , http://hdl.handle.net/10962/d1011315
- Description: [from the Introduction] The purpose of including Second and Third Generation (STG) rights in a constitution is to provide guidelines to lawmakers to formulate policy and to enable the courts to intervene where these policies are not being implemented satisfactorily. In theory these rights allow citizens to demand from the state access to basic needs, such as adequate land, housing, education, health care, nutrition, and social security. However, this inclusion of rights in the constitution often does not translate into action. The first reason for this is that Second and Third Generation rights may clash with First Generation rights. For example the right to private property may, and in South Africa does, contradict the need for land for the majority. The major problem is whether the policies flowing out of Second and Third Generation rights are pursued with enough vigour by governments, the private sector, primary groups and individuals to overcome this contradiction. In many countries in the world it is the poorest sections of the population, and as Mamdani (1996) pointed out, migrant non-citizens, that bear the brunt of administrative and bureaucratic bungling and neglect.
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- Authors: Roodt, Monty J
- Date: 2008
- Language: English
- Type: Conference paper
- Identifier: vital:6318 , http://hdl.handle.net/10962/d1011315
- Description: [from the Introduction] The purpose of including Second and Third Generation (STG) rights in a constitution is to provide guidelines to lawmakers to formulate policy and to enable the courts to intervene where these policies are not being implemented satisfactorily. In theory these rights allow citizens to demand from the state access to basic needs, such as adequate land, housing, education, health care, nutrition, and social security. However, this inclusion of rights in the constitution often does not translate into action. The first reason for this is that Second and Third Generation rights may clash with First Generation rights. For example the right to private property may, and in South Africa does, contradict the need for land for the majority. The major problem is whether the policies flowing out of Second and Third Generation rights are pursued with enough vigour by governments, the private sector, primary groups and individuals to overcome this contradiction. In many countries in the world it is the poorest sections of the population, and as Mamdani (1996) pointed out, migrant non-citizens, that bear the brunt of administrative and bureaucratic bungling and neglect.
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The Cultural Use of the Wild Olive Tree by the amaXhosa People in the Eastern Cape Province of South Africa:
- Cocks, Michelle L, Dold, Anthony P
- Authors: Cocks, Michelle L , Dold, Anthony P
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141314 , vital:37961 , DOI: 10.1558/jsrnc.v2i3.292
- Description: The cultural meanings of harvested plants have for the most part been ignored in academic research on non-timber forest products (NTFPs) in southern Africa. Historically scientists have tended to ignore the complex relationships between nature and culture. Given the country's unique political and economic past and the current search for sustainable use of natural resources, a focus on the convergence of natural science and cultural diversity is important at this time. Empirical data on cultural practices is being collected in order to develop fresh and relevant insights into the complex relationships between culture and bítKÜversity. The purpose of this paper is to demonstrate that the concept of culture needs to be brought into our understanding of the role of NTFPs. We dtxrument the use and value of a specific tree, Olea europaea L. subsp. africana (Mill.) P,S. Green, called Umiicjuma in the Xhosa language, for cultural purposes, by both rural and urban households.
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- Authors: Cocks, Michelle L , Dold, Anthony P
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141314 , vital:37961 , DOI: 10.1558/jsrnc.v2i3.292
- Description: The cultural meanings of harvested plants have for the most part been ignored in academic research on non-timber forest products (NTFPs) in southern Africa. Historically scientists have tended to ignore the complex relationships between nature and culture. Given the country's unique political and economic past and the current search for sustainable use of natural resources, a focus on the convergence of natural science and cultural diversity is important at this time. Empirical data on cultural practices is being collected in order to develop fresh and relevant insights into the complex relationships between culture and bítKÜversity. The purpose of this paper is to demonstrate that the concept of culture needs to be brought into our understanding of the role of NTFPs. We dtxrument the use and value of a specific tree, Olea europaea L. subsp. africana (Mill.) P,S. Green, called Umiicjuma in the Xhosa language, for cultural purposes, by both rural and urban households.
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The Late Glacial and Holocene avifauna of the island of St Helena, South Atlantic Ocean
- Authors: Lewis, Colin A
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6702 , http://hdl.handle.net/10962/d1006738
- Description: Bird bones from unconsolidated sediments provide a record of the changing avifauna of St Helena from the Late Glacial, at ~ 14000BP, until the present. Changes in avifauna apparently reflect climatic and associated ecological conditions, as well as the effects of human occupation since the island was discovered in 1502. Introduced mammals decimated birds in the seventeenth century and seven endemic species are now extinct, while seven other species are locally extinct. At least nine species that now breed on St Helena have been introduced anthropogenically to the island since it was discovered. The failure to find evidence of native songbirds in the former woodlands of the interior of the island deserves explanation.
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- Authors: Lewis, Colin A
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6702 , http://hdl.handle.net/10962/d1006738
- Description: Bird bones from unconsolidated sediments provide a record of the changing avifauna of St Helena from the Late Glacial, at ~ 14000BP, until the present. Changes in avifauna apparently reflect climatic and associated ecological conditions, as well as the effects of human occupation since the island was discovered in 1502. Introduced mammals decimated birds in the seventeenth century and seven endemic species are now extinct, while seven other species are locally extinct. At least nine species that now breed on St Helena have been introduced anthropogenically to the island since it was discovered. The failure to find evidence of native songbirds in the former woodlands of the interior of the island deserves explanation.
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Trophic ecology of dominant zooplankton and macrofauna in a temperate, oligotrophic South African estuary: a fatty acid approach
- Richoux, Nicole B, Froneman, P William
- Authors: Richoux, Nicole B , Froneman, P William
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/478883 , vital:78235 , https://doi.org/10.3354/meps07323
- Description: Fatty acid profiles of food sources, dominant zooplankton, macrofauna and a few small ichthyofauna in a temperate estuary on the southeastern coast of South Africa were used to trace the original carbon sources and the degree of feeding plasticity of consumers within an oligotrophic environment. Fatty acid analysis is seldom used to examine food web ecology in estuaries, as these systems are typically highly complex owing to the variety of potential food sources and the variable nature of detritus. We hypothesized that generalist consumers would exhibit similar and overlapping fatty acid compositions, whereas any specialist consumers would ‘stand out’as they may contain high proportions of fatty acids specific to their preferred food sources. Within-species variation was very small in the food sources, and Principal Component Analysis (PCA) allowed resolution of most species and sample types into distinct clusters. Variation of fatty acid composition was greater within the consumers, with PCA resolving several clusters by collection location within the site and feeding mode of the animals (suspension feeders, grazers and omnivores). We considered the fatty acid profiles (with particular reference to polyunsaturated fatty acids and essential fatty acids) of the consumers in relation to the food sources to determine which organisms played significant roles in the sequestration and cycling of high quality organic material within the estuary.
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- Authors: Richoux, Nicole B , Froneman, P William
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/478883 , vital:78235 , https://doi.org/10.3354/meps07323
- Description: Fatty acid profiles of food sources, dominant zooplankton, macrofauna and a few small ichthyofauna in a temperate estuary on the southeastern coast of South Africa were used to trace the original carbon sources and the degree of feeding plasticity of consumers within an oligotrophic environment. Fatty acid analysis is seldom used to examine food web ecology in estuaries, as these systems are typically highly complex owing to the variety of potential food sources and the variable nature of detritus. We hypothesized that generalist consumers would exhibit similar and overlapping fatty acid compositions, whereas any specialist consumers would ‘stand out’as they may contain high proportions of fatty acids specific to their preferred food sources. Within-species variation was very small in the food sources, and Principal Component Analysis (PCA) allowed resolution of most species and sample types into distinct clusters. Variation of fatty acid composition was greater within the consumers, with PCA resolving several clusters by collection location within the site and feeding mode of the animals (suspension feeders, grazers and omnivores). We considered the fatty acid profiles (with particular reference to polyunsaturated fatty acids and essential fatty acids) of the consumers in relation to the food sources to determine which organisms played significant roles in the sequestration and cycling of high quality organic material within the estuary.
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Development of a regional GPS-based ionospheric TEC model for South Africa
- Opperman, Ben D L, Cilliers, Pierre J, McKinnell, Lee-Anne, Haggard, Raymond
- Authors: Opperman, Ben D L , Cilliers, Pierre J , McKinnell, Lee-Anne , Haggard, Raymond
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6799 , http://hdl.handle.net/10962/d1003925
- Description: Advances in South African space physics research and related disciplines require better spatial and time resolution ionospheric information than was previously possible with the existing ionosonde network. A GPS-based, variable degree adjusted spherical harmonic (ASHA) model was developed for near real-time regional ionospheric total electron content (TEC) mapping over South Africa. Slant TEC values along oblique GPS signal paths are quantified from a network of GPS receivers and converted to vertical TEC by means of the single layer mapping function. The ASHA model coefficients and GPS differential biases are estimated from vertical TEC at the ionospheric pierce points and used to interpolate TEC at any location within the region of interest. Diurnal TEC variations with one minute time resolution and time-varying 2D regional TEC maps are constructed. In order to validate the ASHA method, simulations with an IRI ionosphere were performed, while the ASHA results from actual data were compared with two independent GPS-based methodologies and measured ionosonde data.
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- Authors: Opperman, Ben D L , Cilliers, Pierre J , McKinnell, Lee-Anne , Haggard, Raymond
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6799 , http://hdl.handle.net/10962/d1003925
- Description: Advances in South African space physics research and related disciplines require better spatial and time resolution ionospheric information than was previously possible with the existing ionosonde network. A GPS-based, variable degree adjusted spherical harmonic (ASHA) model was developed for near real-time regional ionospheric total electron content (TEC) mapping over South Africa. Slant TEC values along oblique GPS signal paths are quantified from a network of GPS receivers and converted to vertical TEC by means of the single layer mapping function. The ASHA model coefficients and GPS differential biases are estimated from vertical TEC at the ionospheric pierce points and used to interpolate TEC at any location within the region of interest. Diurnal TEC variations with one minute time resolution and time-varying 2D regional TEC maps are constructed. In order to validate the ASHA method, simulations with an IRI ionosphere were performed, while the ASHA results from actual data were compared with two independent GPS-based methodologies and measured ionosonde data.
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Global diversity of mayflies (Ephemeroptera, Insecta) in freshwater
- Barber-James, Helen M, Gattolliat, Jean-Luc, Sartori, Michel, Hubbard, Michael D
- Authors: Barber-James, Helen M , Gattolliat, Jean-Luc , Sartori, Michel , Hubbard, Michael D
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:7002 , http://hdl.handle.net/10962/d1008361
- Description: The extant global Ephemeroptera fauna is represented by over 3,000 described species in 42 families and more than 400 genera. The highest generic diversity occurs in the Neotropics, with a correspondingly high species diversity, while the Palaearctic has the lowest generic diversity, but a high species diversity. Such distribution patterns may relate to how long evolutionary processes have been carrying on in isolation in a bioregion. Over an extended period, there may be extinction of species, but evolution of more genera. Dramatic extinction events such as the K-T mass extinction have affected current mayfly diversity and distribution. Climatic history plays an important role in the rate of speciation in an area, with regions which have been climatically stable over long periods having fewer species per genus, when compared to regions subjected to climatic stresses, such as glaciation. A total of 13 families are endemic to specific bioregions, with eight among them being monospecific. Most of these have restricted distributions which may be the result of them being the relict of a previously more diverse, but presently almost completely extinct family, or may be the consequence of vicariance events, resulting from evolution due to long-term isolation.
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- Authors: Barber-James, Helen M , Gattolliat, Jean-Luc , Sartori, Michel , Hubbard, Michael D
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:7002 , http://hdl.handle.net/10962/d1008361
- Description: The extant global Ephemeroptera fauna is represented by over 3,000 described species in 42 families and more than 400 genera. The highest generic diversity occurs in the Neotropics, with a correspondingly high species diversity, while the Palaearctic has the lowest generic diversity, but a high species diversity. Such distribution patterns may relate to how long evolutionary processes have been carrying on in isolation in a bioregion. Over an extended period, there may be extinction of species, but evolution of more genera. Dramatic extinction events such as the K-T mass extinction have affected current mayfly diversity and distribution. Climatic history plays an important role in the rate of speciation in an area, with regions which have been climatically stable over long periods having fewer species per genus, when compared to regions subjected to climatic stresses, such as glaciation. A total of 13 families are endemic to specific bioregions, with eight among them being monospecific. Most of these have restricted distributions which may be the result of them being the relict of a previously more diverse, but presently almost completely extinct family, or may be the consequence of vicariance events, resulting from evolution due to long-term isolation.
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