Aardvark burrows: a potential resource for animals in arid and semi-arid environments
- Authors: Whittington-Jones, Gareth M , Bernard, Ric T F , Parker, Daniel M
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443852 , vital:74166 , https://doi.org/10.1080/15627020.2011.11407509
- Description: Arid and semi-arid environments are characterized by extreme fluctuations in temperature and low rainfall, which present significant challenges to the animals inhabiting these areas. However, the presence of burrows may allow animals to avoid climatic extremes and predators and may act as valuable foraging sites. We assessed the microhabitat conditions (maximum and minimum temperature, relative humidity and seed abundance) of aardvark (Orycteropus afer) burrows in relation to paired non-burrow areas at three sites in South Africa. We also describe the extent to which they are used as resources by other vertebrates. Maximum temperatures were significantly lower and minimum temperatures and relative humidity values were significantly higher inside the burrows than outside. The concentration of seeds inside the burrows and at the paired non-burrow sites was similar. Twenty-seven vertebrate species (21 mammals, two birds, three reptiles and one amphibian) were recorded making use of the burrows and it is likely that these species accrue benefits (e.g. a buffered microclimate) from burrow use. However, our sampling was biased towards mammals and nocturnal species. Consequently, we recommend further work to establish the overall reliance of vertebrate taxa on aardvark burrows in arid and semi-arid environments.
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Adoption, use and perception of Australian acacias around the world
- Authors: Kull, Christian A , Shackleton, Charlie M , Cunningham, Peter J , Ducatillon, Catherine , Dufour-Dror, Jean-Mark , Esler, Karen J , Friday, James B , Gouveia, António C , Griffin, A R , Marchante, Elizabete , Midgley, Steven J , Pauchard, Aníbal , Rangan, Haripriya , Richardson, David M , Rinaudo, Tony , Tassin, Jacques , Urgenson, Lauren S , van Maltitz, Graham P , Zenni, Rafael D , Zylstra, Matthew J
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182149 , vital:43804 , xlink:href="https://doi.org/10.1111/j.1472-4642.2011.00783.x"
- Description: To examine the different uses and perceptions of introduced Australian acacias (wattles; Acacia subgenus Phyllodineae) by rural households and communities. Eighteen landscape-scale case studies around the world, in Vietnam, India, Réunion, Madagascar, South Africa, Congo, Niger, Ethiopia, Israel, France, Portugal, Brazil, Chile, Dominican Republic and Hawai‘i. Qualitative comparison of case studies, based on questionnaire sent to network of acacia researchers. Information based on individual knowledge of local experts, published and unpublished sources. We propose a conceptual model to explain current uses and perceptions of introduced acacias. It highlights historically and geographically contingent processes, including economic development, environmental discourses, political context, and local or regional needs. Four main groupings of case studies were united by similar patterns: (1) poor communities benefiting from targeted agroforestry projects; (2) places where residents, generally poor, take advantage of a valuable resource already present in their landscape via plantation and/or invasion; (3) regions of small and mid-scale tree farmers participating in the forestry industry; and (4) a number of high-income communities dealing with the legacies of former or niche use of introduced acacia in a context of increased concern over biodiversity and ecosystem services. Economic conditions play a key role shaping acacia use. Poorer communities rely strongly on acacias (often in, or escaped from, formal plantations) for household needs and, sometimes, for income. Middle-income regions more typically host private farm investments in acacia woodlots for commercialization. Efforts at control of invasive acacias must take care to not adversely impact poor dependent communities.
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Advances in entomological methods for death time estimation
- Authors: Villet, Martin H , Amendt, Jens
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441722 , vital:73910 , https://doi.org/10.1007/978-1-61779-249-6_11
- Description: The development of entomological methods for estimating the time of death has been rapid in the last decade, and new methods are on the horizon. These developments are reviewed with specific reference to experimental design, established and new techniques, and mathematical modelling for forensic retrodiction. The techniques include the use of electron microscopy, magnetic resonance imaging, computed tomography, cuticular hydrocarbon profiles, and real-time PCR to estimate the age of immature insects found on corpses, based on their stage of development. Near-infrared spectrograph and pteridine fluorescence techniques can be applied to this task on adult insects. The use of ecological succession in the carrion insect community is also introduced briefly. Finally, the creation and uses of standard techniques in forensic entomology is discussed. We recommend that two steps in this standardisation process are that physiological and ecological studies should be reported in physiological time wherever this is appropriate, and that the type of post-mortem interval being estimated should be stipulated more explicitly than is currently common.
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Africa: unity, sovereignty and sorrow A book review
- Authors: Matthews, Sally
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142387 , vital:38075 , DOI: 10.1080/02589001.2011.562007
- Description: This ambitious book begins with the statement ‘By and large, the states of sub-Saharan Africa are failures’ (p. 1) and then sets out to explain state failure in Africa and to provide some ‘rational policy fantasies’ in response to this failure. The book builds on the work of scholars like Robert Jackson, William Reno and Jeffrey Herbst, with the particular focus of Englebert's book being on the domestic implications of the unconditional recognition of the sovereignty of African states. African states are internationally recognised despite lacking the features and not being able to perform the functions typically associated with statehood. Englebert's interest is to examine some of the domestic effects of this unconditional international recognition.
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African carrion ecosystems and their insect communities in relation to forensic entomology
- Authors: Villet, Martin H
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442439 , vital:73984 , http://www.globalsciencebooks.info/Online/GSBOnline/OnlinePT_5_1.html
- Description: African carrion communities contain representatives of the same families that occur in carrion communities on other continents. Checklists and identification guides are tabulated, and the natural histories of core members of the terrestrial community are outlined. Because of strong phylogenetic trends in the biology of the families, the species are effectively ecological surrogates of their relatives elsewhere. These phylogenetic trends also allow the definition of a set of guilds of functionally equivalent species that unify the study of carrion communities world-wide, and a revised suite of guilds is described with both synecological and forensic purposes in mind. Although the decomposition process has been arbitrarily subdivided into stages, they have little direct relation to the dynamics of the carrion community, and should be treated as landmarks rather than phases. Community turnover follows a qualitatively predictable succession, with the greatest species richness and diversity around the ecotone-like transition from ‘wet-phase’ to ‘dry-phase’ carrion habitats. These habitats are differentiated along interacting ecological gradients of dietary quality, competition, and risk of predation, which are important to the core guilds. Competition and predation have strong effects on population dynamics of community members, but link particular species only weakly, so that the succession pattern largely reflects the autecology of the individual species. Discrete waves of species are absent, which increases the temporal resolution, and therefore the forensic value, of the succession as a ‘clock’. The forensic significance of various aspects of community and trophic dynamics are discussed, and means of applying ecological theory to investigations are reviewed.
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African Languages And ICT Education
- Authors: Dalvit, Lorenzo , Murray, Sarah , Terzoli, Alfredo
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431166 , vital:72750 , https://www.scitepress.org/Papers/2011/33507/33507.pdf
- Description: In South Africa, English plays a dominant role compared to African lan-guages in empowering domain. Better access to Education through the use of African languages is an object of heated debate. This paper shows that an intervention involving the use of an African language in the domain of ICT Education can change the attitudes of Black universi-ty students. The methodology used included a survey with preliminary and follow-up questionnaires and interviews and an intervention involv-ing the use of localised software and of an on-line glossary of computer terms translated, explained and exemplified in an African language (isiXhosa). This experience increased the support for the use of African languages as additional LoLT, even in the English-dominated field of study of Computer Science. This is an initial step towards promoting linguistic equality between English and African languages and social equality between their speakers.
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Age validation, growth, mortality, and demographic modeling of spotted gully shark (Triakis megalopterus) from the southeast coast of South Africa
- Authors: Booth, Anthony J , Foulis, Alan J , Smale, Malcolm J
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123630 , vital:35466 , https://spo.nmfs.noaa.gov/sites/default/files/pdf-content/2011/1091/booth.pdf
- Description: This study documents validation of vertebral band-pair formation in spotted gully shark (Triakis megalopterus) with the use of f luorochrome injection and tagging of captive and wild sharks over a 21-year period. Growth and mortality rates of T. megalopterus were also estimated and a demographic analysis of the species was conducted. Of the 23 OTC (oxytetracycline) -marked vertebrae examined (12 from captive and 11 from wild sharks), seven vertebrae (three from captive and four from wild sharks) exhibited chelation of the OTC and f luoresced under ultraviolet light. It was concluded that a single opaque and translucent band pair was deposited annually up to at least 25 years of age, the maximum age recorded. Reader precision was assessed by using an index of average percent error calculated at 5%. No significant differences were found between male and female growth patterns (P>0.05), and von Bertalanffy growth model parameters for combined sexes were estimated to be L∞=1711.07 mm TL, k=0.11/yr and t0= –2.43 yr (n=86). Natural mortality was estimated at 0.17/yr. Age at maturity was estimated at 11 years for males and 15 years for females. Results of the demographic analysis showed that the population, in the absence of fishing mortality, was stable and not significantly different from zero and particularly sensitive to overfishing. At the current age at first capture and natural mortality rate, the fishing mortality rate required to result in negative population growth was low at F>0.004/ yr. Elasticity analysis revealed that juvenile survival was the principal factor in explaining variability in population growth rate.
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An attempt to constrain the age, duration, and eruptive history of the Karoo flood basalt: Naude's Nek section (South Africa)
- Authors: Moulin, Maud , Fluteau, Frédéric , Courtillot, Vincent , Marsh, Julian S , Delpech, Guillaume , Quidelleur, Xavier , Gérard, Martine , Jay, Anne E
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145022 , vital:38401 , https://doi.org/10.1029/2011JB008210
- Description: We have carried out paleomagnetic sampling of a ∼750 m sequence of the Karoo large igneous province (Naude's Nek Pass, South Africa). K‐Ar dating (Cassignol‐Gillot) has been performed on four samples from the 650 m upper unit (mean age 179.2 ± 1.8 Ma) and a sample from the lower unit (184.8 ± 2.6 Ma). A succession of two phases of volcanism is suggested. The lower 25 flows (115 m thick) have recorded a reversed polarity; the next 23 flows (135 m thick) are transitional and contribute a detailed record of the “Van Zijl” (1962) Jurassic reversal.
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An evaluation of lightweight classification methods for identifying malicious URLs
- Authors: Egan, Shaun P , Irwin, Barry V W
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429839 , vital:72644 , 10.1109/ISSA.2011.6027532
- Description: Recent research has shown that it is possible to identify malicious URLs through lexical analysis of their URL structures alone. This paper intends to explore the effectiveness of these lightweight classification algorithms when working with large real world datasets including lists of malicious URLs obtained from Phishtank as well as largely filtered be-nign URLs obtained from proxy traffic logs. Lightweight algorithms are defined as methods by which URLs are analysed that do not use exter-nal sources of information such as WHOIS lookups, blacklist lookups and content analysis. These parameters include URL length, number of delimiters as well as the number of traversals through the directory structure and are used throughout much of the research in the para-digm of lightweight classification. Methods which include external sources of information are often called fully featured classifications and have been shown to be only slightly more effective than a purely lexical analysis when considering both false-positives and false-negatives. This distinction allows these algorithms to be run client side without the introduction of additional latency, but still providing a high level of accu-racy through the use of modern techniques in training classifiers. Anal-ysis of this type will also be useful in an incident response analysis where large numbers of URLs need to be filtered for potentially mali-cious URLs as an initial step in information gathering as well as end us-er implementations such as browser extensions which could help pro-tect the user from following potentially malicious links. Both AROW and CW classifier update methods will be used as prototype implementa-tions and their effectiveness will be compared to fully featured analysis results. These methods are interesting because they are able to train on any labelled data, including instances in which their prediction is cor-rect, allowing them to build a confidence in specific lexical features. This makes it possible for them to be trained using noisy input data, making them ideal for real world applications such as link filtering and information gathering.
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An Evaluation of Trading Bands as Indicators for Network Telescope Datasets
- Authors: Cowie, Bradley , Irwin, Barry V W
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428013 , vital:72480 , https://www.researchgate.net/profile/Barry-Ir-win/publication/326225071_An_Evaluation_of_Trading_Bands_as_Indicators_for_Network_Telescope_Datasets/links/5b3f231a4585150d2309e1c0/An-Evaluation-of-Trading-Bands-as-Indicators-for-Network-Telescope-Datasets.pdf
- Description: Large scale viral outbreaks such as Conficker, the Code Red worm and the Witty worm illustrate the importance of monitoring malevolent activity on the Internet. Careful monitoring of anomalous traffic allows organiza-tions to react appropriately and in a timely fashion to minimize economic damage. Network telescopes, a type of Internet monitor, provide ana-lysts with a way of decoupling anomalous traffic from legitimate traffic. Data from network telescopes is used by analysts to identify potential incidents by comparing recent trends with historical data. Analysis of network telescope datasets is complicated by the large quantity of data present, the number of subdivisions within the data and the uncertainty associated with received traffic. While there is considerable research being performed in the field of network telescopes little of this work is concerned with the analysis of alternative methods of incident identifi-cation. This paper considers trading bands, a subfield of technical analysis, as an approach to identifying potential Internet incidents such as worms. Trading bands construct boundaries that are used for meas-uring when certain quantities are high or low relative to recent values. This paper considers Bollinger Bands and associated Bollinger Indica-tors, Price Channels and Keltner Channels. These techniques are evaluated as indicators of malevolent activity by considering how these techniques react to incidents indentified in the captured data from a network telescope.
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An illustrated leaflet containing antiretroviral information targeted for low-literate readers: development and evaluation
- Authors: Dowse, Roslind , Ramela, Thato , Browne, Sara H
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156731 , vital:40043 , https://doi.org/10.1016/j.pec.2011.01.013
- Description: To apply a dual visual/textual modal approach in developing and evaluating a medicine information leaflet with pictograms suitable for low-literate HIV/AIDS patients. To identify and recommend best practices in this type of information design.
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Associations in ephemeral systems: the lack of trophic relationships between sandhoppers and beach wrack
- Authors: Porri, Francesca , Hill, Jaclyn M , McQuaid, Christopher D
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444552 , vital:74250 , https://doi.org/10.3354/meps08951
- Description: In ephemeral systems, material subsidies can play a key role in the persistence and connectivity of populations, especially if the organisms living within them are trophically dependent on imported resources. Sandy beaches are heavily subsidized by organic material of both terrestrial and marine origin. For highly mobile supratidal fringe species, such as amphipods, which are marine but with a high tolerance of aerial conditions, such material potentially provides both food and shelter. We investigated the relationship between beach wrack and amphipods by examining the trophic contribution of allochthonous food sources to sandhopper diets using stable isotope analysis. Replicate samples of the sandhopper Talorchestia capensis and several types of beach wrack (including seagrass, wood and different macrophytes) colonized by these amphipods were collected from 11 sites within one biogeographical region along the south coast of South Africa.
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Becoming African: debating post-apartheid white South African identities
- Authors: Matthews, Sally
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142409 , vital:38077 , DOI: 10.1080/14725843.2011.530440
- Description: The post-apartheid era necessitates the rethinking of white identities in South Africa. One way in which some white South Africans are seeking to redefine themselves is through describing themselves as African. However, claims by white South Africans that they too are Africans have been met with mixed responses from black South Africans. In this article I use contributions to an online university students' forum to explore ways in which some white South Africans are embracing an African identity and to consider ways in which some black South Africans are responding to white South Africans' shifting identities. I use contributions to this forum as a starting point to think about the possibilities and limitations that the embracing of an African identity has for the development of what Frankenberg calls ‘anti-racist forms of whiteness’ among white South Africans.
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Being moved by a way the world is not
- Authors: Jones, Ward E
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275631 , vital:55064 , xlink:href="https://doi.org/10.1007/s11229-009-9522-z"
- Description: At the end of Lecture 3 of The Empirical Stance, Bas van Fraassen suggests that we see the change of view involved in scientific revolutions as being, at least in part, emotional. In this paper, I explore one plausible way of cashing out this suggestion. Someone’s emotional approval of a description of the world, I argue, thereby shows that she takes herself to have reason to take that description seriously. This is true even if she is convinced—as a scientific community is when it considers alternative theories—that this description is false, that it is not the way the world is.
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Biological control of cactaceae in South Africa
- Authors: Paterson, Iain D , Hoffmann, John H , Klein, Hildegard , Mathenge, C W , Neser, Stephan , Zimmermann, Helmuth G
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452308 , vital:75119 , https://hdl.handle.net/10520/EJC32918
- Description: This review is a summary of developments that have contributed to the success of several biological control programmes against invasive cactus species (Cactaceae) that have been worked on in South Africa over the last 12 years. Six potential biological control agents have been identified for the control of Pereskia aculeata Mill. and molecular studies have identified the origin of the South African P. aculeata population. Host-specificity testing is now required for the three most promising of these agents. The successful biological control programme against Opuntia stricta (Haw.) Haw. has resulted in a change in management strategies against this weed in the Kruger National Park and the control of O. stricta is now almost entirely reliant on biological control. Taxonomic problems associated with the identification of Cylindropuntia fulgida var. fulgida (Engelm.) F.M.Knuth var. fulgida have been resolved and an appropriate cochineal insect (Hemiptera: Dactylopiidae) biotype has been released, resulting in substantial declines in Cyl. fulgida var. fulgida populations. A long-term monitoring programme has been initiated to evaluate the progress of this new cochineal insect biotype. The Harrisia mealybug, Hypogeococcus pungens Granara de Willink (Hemiptera: Pseudococcidae), which was originally released on Harrisia martinii (Labour.) Britton and Rose has been collected and redistributed onto Cereus jamacaru DC., where it reduces fruit production and leads to the death of both seedlings and large plants. Resolving taxonomic problems to ensure the correct identification of plant species and the most appropriate biological control biotypes have been key issues that have led to the successful control of several cactaceous weed species in South Africa.
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Biphenyl sorption to different soil clay minerals
- Authors: Tandlich, Roman , Baláž, Štefan
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76869 , vital:30632 , https://doi.org/10.5897/AJAR10.1012
- Description: Only limited information is available in the literature on the role of soil mineral surfaces in the sorption of hydrophobic organic pollutants. This knowledge gap is addressed through the assessment of biphenyl sorption to kaolinite, illite and bentonite; using the batch equilibration technique with incubations lasting 6 or 21 days at 28 ± 2°C in the dark [RT1]. Sorption of biphenyl onto kaolinite followed the Freundlich sorption isotherm, whereas linear sorption isotherms were observed on illite and bentonite [RT2]. The biphenyl sorption partition coefficient on kaolinite ranged from 0.1 to 9.1 cm3.g-1 after 6 days and no sorption was observed after 21 days. This could have been caused by a completely reversible sorption or a loss of binding capacity after 21 days [RT3]. The respective values of the biphenyl sorption partition coefficient on illite and bentonite ranged from 20.3 ± 0.3 to 120 ± 8 cm3.g-1.Sorption equilibrium on the internal clay surfaces was reached after 6 days, as indicated by the sorption data for illite and bentonite [RT4]. Access of biphenyl molecules to the internal clay surfaces is a function of the ionic strength of soil solution and the soil organic matter is the dominant site for biphenyl sorption after 6 to 21 days.
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Climate‐driven genetic divergence of limpets with different life histories across a southeast African marine biogeographic disjunction: different processes, same outcome
- Authors: Teske, Peter R , Papadopoulos, Isabelle , Mmonwa, Kolobe L , Matumba, Tshifhiwa G , McQuaid, Christopher D , Barker, Nigel P , Beheregaray, Luciano B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/445420 , vital:74385 , https://doi.org/10.1111/j.1365-294X.2011.05307.x
- Description: Genetic divergence among populations of marine broadcast spawners in the absence of past geological barriers presents an intriguing challenge to understanding speciation in the sea. To determine how differences in life history affect genetic divergence and demographic histories across incomplete dispersal barriers, we conducted a comparative phylogeographic study of three intertidal limpets (Siphonaria spp.) represented on either side of a biogeographic disjunction separating tropical and subtropical marine provinces in southeastern Africa. Using a combination of mitochondrial and nuclear sequence data, we identified two distinct evolutionary lineages each in both Siphonaria concinna (a planktonic disperser) and S. nigerrima (a direct developer), and panmixia in a second planktonic disperser, S. capensis.
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Comfortably numb: Crump unveiled—a review of the 2011 Alan Crump retrospective exhibitio
- Authors: Cooper, Paul S
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147924 , vital:38685 , DOI:10.1080/00043389.2011.11877152
- Description: Writing can at times be difficult. It is not without considerable anxiety that I undertake to write this particular review. Perhaps I should offer a short qualifier: this is not strictly a review but rather a collection of ideas around the works and their arrangement, as well as my own musings and reflections on Crump. I want to pick up on what I identify to be an approach that personalises Crump as a professor, colleague and artist (we find this tone embedded throughout the accompanying exhibition catalogue). 1 I have chosen to structure this essay using a series of trigger headings, some provocative and possibly even inflammatory, others more neutral and concerned with getting to the core of what this retrospective and posthumous show is all about. All the while my thinking is to channel a sense (or lack thereof, as it may turn out) of my own experience of his work and person.
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Comparative behavior of conjugates of tantalum phthalocyanines with gold nanoparticles or single walled carbon nanotubes towards bisphenol A electrocatalysis
- Authors: Chauke, Vongani P , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247152 , vital:51551 , xlink:href="https://doi.org/10.1016/j.jelechem.2011.06.019"
- Description: The characterization of tantalum phthalocyanine conjugates with gold nanoparticles and single wall carbon nanotubes as well as their electrocatalytic oxidation of bisphenol A is hereby presented. The formation of the conjugates was confirmed by X-ray diffraction and transmission electron microscope techniques. Single walled carbon nanotube conjugates of TaPc complexes showed the best catalysis as well as less passivation for bisphenol A detection and significant recovery of ∼98% compared to gold nanoparticle conjugates.
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Comparative structural bioinformatics analysis of Bacillus amyloliquefaciens chemotaxis proteins within Bacillus subtilis group
- Authors: Yssel, Anna , Reva, Oleg , Tastan Bishop, Özlem
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123966 , vital:35521 , https://doi.10.1007/s00253-011-3582-y
- Description: Chemotaxis is a process in which bacteria sense their chemical environment and move towards more favorable conditions. Since plant colonization by bacteria is a multifaceted process which requires a response to the complex chemical environment, a finely tuned and sensitive chemotaxis system is needed. Members of the Bacillus subtilis group including Bacillus amyloliquefaciens are industrially important, for example, as bio-pesticides. The group exhibits plant growth-promoting characteristics, with different specificity towards certain host plants. Therefore, we hypothesize that while the principal molecular mechanisms of bacterial chemotaxis may be conserved, the bacterial chemotaxis system may need an evolutionary tweaking to adapt it to specific requirements, particularly in the process of evolution of free-living soil organisms, towards plant colonization behaviour. To date, almost nothing is known about what parts of the chemotaxis proteins are subjected to positive amino acid substitutions, involved in adjusting the chemotaxis system of bacteria during speciation. In this novel study, positively selected and purified sites of chemotaxis proteins were calculated, and these residues were mapped onto homology models that were built for the chemotaxis proteins, in an attempt to understand the spatial evolution of the chemotaxis proteins. Various positively selected amino acids were identified in semi-conserved regions of the proteins away from the known active sites.
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