145 Works

Cattaneo-Christov Heat Flux on an MHD 3D Free Convection Casson Fluid Flow Over a Stretching Sheet

D. Gowri SHANKAR, C.S.K. RAJU, M.S. Jagadeesh KUMAR & Oluwole Daniel MAKINDE
In this investigation, we analyze the magnetohydrodynamic (MHD) three-dimensional (3D) flow of Casson fluid over a stretching sheet using non-Darcy porous medium with heat source/sink. We also consider the Cattaneo-Christov heat flux and Joule effect. The governing partial differential equations (PDEs) are transformed into ordinary differential equations (ODEs) using suitable transformations and solved by using the shooting technique. The effects of the non-dimensional governing parameters on velocity and temperature profiles are discussed with the graphs....

Data from: Between the Cape Fold Mountains and the deep blue sea: comparative phylogeography of selected codistributed ectotherms reveals asynchronous cladogenesis. Sampling locations and MaxEnt input files

Angus Myburgh
We compare the phylogeographic structure of thirteen codistributed ectotherms including four reptiles (a snake, a legless skink and two tortoise species) and nine invertebrates (six freshwater crabs and three velvet worm species) to test the presence of congruent evolutionary histories. Phylogenies were estimated and dated using maximum likelihood and Bayesian methods with combined mitochondrial and nuclear DNA sequence datasets. All taxa demonstrated a marked east/west phylogeographic division, separated by the Cape Fold Mountain range. Phylogeographic...

Data and R scripts from: Assemblage reorganisation of South African dragonflies due to climate change

Ashleigh Basel
Aim: Climate change is expected to cause large shifts in species assemblages such as dragonflies and damselflies (Insecta: Odonata). Here we assess the influence of environmental drivers of turnover on Odonata assemblages. Secondly, we map the predicted spatial variation in species composition, first as a gradient of assemblage similarity, and then as discrete bioregions delineating major areas of odonate endemism. Finally, we map the magnitude of expected change in species turnover in response to climate...

Landscape genetics Afromontane forest birds - microsatellite data

Jake Mulvaney, Conrad Matthee & Michael Cherry
Species confined to naturally fragmented habitats may exhibit intrinsic population complexity which may challenge interpretations of species response to anthropogenic landscape transformation. In South Africa, where native forests are naturally fragmented, forest‐dependent birds have undergone range declines since 1992, most notably among insectivores. These insectivores appear sensitive to the quality of natural matrix habitats, and it is unknown whether transformation of the landscape matrix has disrupted gene flow in these species. We undertook a landscape...

Untangling the structural and molecular mechanisms underlying colour and rapid colour change in a lizard, Agama atra

Michael Nicolai, Liliana D'Alba, Jonathan Goldenberg, Yannick Gansemans, Filip Van Nieuwerbrugh, Susana Clusella-Trullas & Matthew Shawkey
With functions as diverse as communication, protection and thermoregulation, colouration is one of the most important traits in lizards. The ability to change colour as a function of varying social and environmental conditions is thus an important innovation. While colour change is present in animals ranging from squids, to fish and reptiles, not much is known about the mechanisms behind it. Traditionally, colour change was attributed to migration of pigments, in particular melanin. More recent...

Microsatellite genotype data from seven loci for a phylogeographic/population genetic study of the South African endemic freshwater crab Potamonautes lividus sampled from eight localities in the KwaZulu-Natal and Eastern Cape provinces in South Africa

Savel Daniels
During the present study, the phylogeography of the only southern African IUCN Red Listed vulnerable (VU) freshwater crab, Potamonautes lividus was investigated by surveying several localities in the Eastern Cape and KwaZulu-Natal provinces in South Africa. Both nuclear and mitochondrial DNA markers were used, and it was hypothesized, that marked genetic differentiation should be present, while niche modeling was undertaken to explore the distribution of the species along the east coast of South Africa. Further,...

Data from: Plant dispersal in the sub-Antarctic inferred from anisotropic genetic structure

Céline Born, Peter C. Le Roux, Colin Spohr, Melodie A. McGeoch & Bettine Jansen Van Vuuren
Climatic conditions and landscape features often strongly affect species’ local distribution patterns, dispersal, reproduction and survival, and may therefore have considerable impacts on species' fine-scale spatial genetic structure (SGS). In this paper we demonstrate the efficacy of combining fine-scale SGS analyses with isotropic and anisotropic spatial autocorrelation techniques to infer the impact of wind patterns on plant dispersal processes. We genotyped 1304 Azorella selago (Apiaceae) specimens, a wind-pollinated and wind-dispersed plant, from four populations distributed...

Data from: Tree species diversity promotes aboveground carbon storage through functional diversity and functional dominance

Sylvanus Mensah, Ruan Veldtman, Achille E. Assogbadjo, Romain Glèlè Kakaï & Thomas Seifert
The relationship between biodiversity and ecosystem function has increasingly been debated as the cornerstone of the processes behind ecosystem services delivery. Experimental and natural field-based studies have come up with nonconsistent patterns of biodiversity–ecosystem function, supporting either niche complementarity or selection effects hypothesis. Here, we used aboveground carbon (AGC) storage as proxy for ecosystem function in a South African mistbelt forest, and analyzed its relationship with species diversity, through functional diversity and functional dominance. We...

Data from: Pollination, mating and reproductive fitness in a plant population with bimodal floral-tube length

Bruce Anderson, Anton Pauw, William W. Cole, Spencer C.H. Barrett & S. C. H. Barrett
Mating patterns and natural selection play important roles in determining whether genetic polymorphisms are maintained or lost. Here, we document an atypical population of Lapeirousia anceps (Iridaceae) with a bimodal distribution of floral-tube length and investigate the reproductive mechanisms associated with this pattern of variation. Flowers were visited exclusively by the long-proboscid fly Moegistorhynchus longirostris (Nemestrinidae), which exhibited a unimodal distribution of proboscis length and displayed a preference for long-tubed phenotypes. Despite being visited by...

Data from: When homoplasy mimics hybridization: a case study of Cape hakes (Merluccius capensis and M. paradoxus)

Romina Henriques, Sophie Von Der Heyden & Conrad A. Matthee
In the marine environment, an increasing number of studies have documented introgression and hybridization using genetic markers. Hybridization appears to occur preferentially between sister-species, with the probability of introgression decreasing with an increase in evolutionary divergence. Exceptions to this pattern were reported for the Cape hakes (Merluccius capensis and M. paradoxus), two distantly related Merluciidae species that diverged 3–4.2 million years ago. Yet, it is expected that contemporary hybridization between such divergent species would result...

Data from: Biogeography and host-related factors trumps parasite life-history: limited congruence among the genetic structures of specific ectoparasitic lice and their rodent hosts

Nina Du Toit, Sonja Matthee, Bettine J. Van Vuuren & Conrad A. Matthee
Parasites and hosts interact across both micro- and macroevolutionary scales where congruence among their phylogeographic and phylogenetic structures may be observed. Within southern Africa, the four-striped mouse genus, Rhabdomys, is parasitized by the ectoparasitic sucking louse, Polyplax arvicanthis. Molecular data recently suggested the presence of two cryptic species within P. arvicanthis that are sympatrically distributed across the distributions of four putative Rhabdomys species. We tested the hypotheses of phylogeographic congruence and cophylogeny among the two...

Data from: The influence of pollinator phylogeography and mate preference on floral divergence in a sexually deceptive daisy

Marinus L. De Jager & Allan G. Ellis
Divergent mate preferences and subsequent genetic differentiation between populations has been demonstrated, but its effects on interspecific interactions are unknown. Associated species exploiting these mate preferences, for example, may diverge to match local preferences. We explore this idea in the sexually deceptive, fly-mimicking daisy, Gorteria diffusa, by testing for association between genetic structure in the fly pollinator (a proxy for mate preference divergence) and geographic divergence in floral form. If genetic structure in flies influences...

Data from: Dispersal propensity in Tetrahymena thermophila ciliates – a reaction norm perspective

Frank Pennekamp, Katherine A. Mitchell, Alexis Serge Chaine, Nicolas Schtickzelle & Alexis Chaine
Dispersal and phenotypic plasticity are two main ways for species to deal with rapid changes of their environments. Understanding how genotypes (G), environments (E) and their interaction (genotype and environment; G x E) each affects dispersal propensity is therefore instrumental for predicting the ecological and evolutionary responses of species under global change. Here we used an actively dispersing ciliate to quantify the contributions of G, E, and G x E on dispersal propensity, exposing 44...

Data from: Distinct effects of pollinator dependence and self-incompatibility on pollen limitation in South African biodiversity hotspots

James Rodger, Allan G. Ellis & James G. Rodger
Global synthesis indicates that limitation of plant fecundity by pollen receipt (pollen limitation) is positively related to regional plant diversity and is higher for self-incompatible than self-compatible species. While self-incompatible species are always dependent on pollinating agents, self-compatible species may be pollinator-dependent or autofertile. This should cause variation in pollen limitation among self-compatible species, with lower pollen limitation in autofertile species because they do not depend on pollinators. We hypothesized that the intensity of pollen...

Data from: Emergence of weak‐intransitive competition through adaptive diversification and eco‐evolutionary feedbacks

Laure Gallien, Pietro Landi, Cang Hui & David M. Richardson
Indirect biotic interactions—such as intransitive competition—are increasingly recognized as being important in shaping ecological patterns in natural systems. Over long time‐scales, such indirect interactions may affect the evolution of species phenotypes, which in turn can modify these interactions, thereby begetting eco‐evolutionary feedbacks. If indirect intransitive interactions can emerge in situ during lineage diversification, they could profoundly affect species’ phenotypic diversity, temporal stability, and subsequent diversification rates. We address these questions by investigating the conditions under...

Data from: Has snake fang evolution lost its bite? New insights from a structural mechanics viewpoint

Chris Broeckhoven & Anton Du Plessis
Venomous snakes—the pinnacle of snake evolution—are characterized by their possession of venom-conducting fangs ranging from grooved phenotypes characterizing multiple lineages of rear-fanged taxa to tubular phenotypes present in elapids, viperids and atractaspidines. Despite extensive research, controversy still exists on the selective pressures involved in fang phenotype diversification. Here, we test the hypothesis that larger fangs and consequently a shift to an anterior position in the maxilla evolved to compensate for the costs of structural changes,...

Data from: High human papillomavirus (HPV) prevalence in South African adolescents and young women encourages expanded HPV vaccination campaigns

Zizipho Z.A. Mbulawa, Cari Van Schalkwyk, Nai-Chung Hu, Tracy L. Meiring, Shaun Barnabas, Smritee Dabee, Heather Jaspan, Jean-MAri Kriek, Shameem Z. Jaumdally, Etienne Muller, Linda-Gail Bekker, David A. Lewis, Janan Dietrich, Glenda Gray, Jo-Ann S. Passmore, Anna-Lise Williamson & Zizipho Z. A. Mbulawa
Objectives: To investigate prevalence of cervical human papillomavirus (HPV) genotypes to inform HPV vaccination strategy in South Africa and to study factors associated with HPV prevalence. Methods: Sexually active, HIV-negative women, aged 16-22 years recruited from Soweto (n=143) and Cape Town (n=148) were tested for cervical HPV and other genital infections. Results: Overall HPV prevalence was 66.7% (194/291) in young women. Cape Town women were more likely to have multiple HPV infections than the Soweto...

Data from: Reconstructing biological invasions using public surveys: a new approach to retrospectively assess spatio-temporal changes in invasive spread

Nitya Prakash Mohanty & John Measey
DRYAD_bullfrog occupancy_inputInput file for occupancy analyses used in the paper. Data matrix of detection (1)/non-detection(0) of Indian bullfrogs by key informants (obs 1-10) and field survey (obs 11) at 91 sites on the Andaman archipelago.DRYAD_perceptionData used in analyses of perception of the Indian bullfrog among key informants. Categorized as loss, benefit, neutral, and loss-benefit ('both').DRYAD_dispersal hubsData on 'dispersal hubs' and associated introductions within the Andaman archipelago for the Indian bullfrog. Dispersal hubs - Billyground-Nimbudera (BG-ND),...

Data from: Fluff-thieving birds sabotage seed dispersal

Vanya G. Rohwer, Anton Pauw & Paul R. Martin
Characterizing many species interactions as mutualisms can be misleading because some members of the interaction derive greater fitness benefits at the expense of other members. We provide detailed natural history data on a suspected bird–plant mutualism in South Africa where many species of birds use fluffy Eriocephalus seed material to construct their nests, potentially dispersing seeds for the plant. We focus on a common bird, Prinia maculosa, which invests heavily in gathering Eriocephalus material. Prinias...

Data from: Evaluation of Xpert® MTB/RIF assay in induced sputum and gastric lavage samples from young children with suspected tuberculosis from the MVA85A TB vaccine trial

Erick Wekesa Bunyasi, Michele Tameris, Hennie Geldenhuys, Bey-Marrie Schmidt, Angelique Kany Kany Luabeya, Humphrey Mulenga, Thomas J. Scriba, Willem A. Hanekom, Hassan Mahomed, Helen McShane & Mark Hatherill
Objective: Diagnosis of childhood tuberculosis is limited by the paucibacillary respiratory samples obtained from young children with pulmonary disease. We aimed to compare accuracy of the Xpert® MTB/RIF assay, an automated nucleic acid amplification test, between induced sputum and gastric lavage samples from young children in a tuberculosis endemic setting. Methods: We analyzed standardized diagnostic data from HIV negative children younger than four years of age who were investigated for tuberculosis disease near Cape Town,...

Data from: GloPL, a global data base on pollen limitation of plant reproduction

Joanne. M. Bennett, Janette. A. Steets, Jean. H. Burns, Walter Durka, Jana. C. Vamosi, Gerardo Arceo-Gómez, Martin Burd, Laura. A. Burkle, Allan. G Ellis, Leandro Freitas, Junmin Li, James. G. Rodger, Marina Wolowski, Jing Xia, Tia-Lynn Ashman & Tiffany. M. Knight
Plant reproduction relies on transfer of pollen from anthers to stigmas, and the majority of flowering plants depend on biotic or abiotic agents for this transfer. A key metric for characterizing if pollen receipt is insufficient for reproduction is pollen limitation, which is assessed by pollen supplementation experiments. In a pollen supplementation experiment, fruit or seed production by flowers exposed to natural pollination is compared to that following hand pollination either by pollen supplementation (i.e....

Data from: Dated plant phylogenies resolve Neogene climate and landscape evolution in the Cape Floristic Region

Vera Hoffmann, G. Anthony Verboom & Fenton P. D. Cotterill
In the context of molecularly-dated phylogenies, inferences informed by ancestral habitat reconstruction can yield valuable insights into the origins of biomes, palaeoenvironments and landforms. In this paper, we use dated phylogenies of 12 plant clades from the Cape Floristic Region (CFR) in southern Africa to test hypotheses of Neogene climatic and geomorphic evolution. Our combined dataset for the CFR strengthens and refines previous palaeoenvironmental reconstructions based on a sparse, mostly offshore fossil record. Our reconstructions...

Data from: Refuges from fire maintain pollinator-plant interaction networks

Opeyemi Adedoja, Carsten F. Dormann, Temitope Kehinde & Michael J. Samways
Fire is a major disturbance factor in many terrestrial ecosystems, leading to landscape transformation in fire‐prone areas. Species in mutualistic interactions are often highly sensitive to disturbances like fire events, but the degree and complexity of their responses are unclear. We use bipartite insect–flower interaction networks across a recently burned landscape to explore how plant–pollinator interaction networks respond to a recent major fire event at the landscape level, and where fire refuges were present. We...

Leaders’ adaptive identity development in uncertain contexts: Implications for executive coaching

Kathy Bennett

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  • Stellenbosch University
  • University of Cape Town
  • South African National Biodiversity Institute
  • University of Pretoria
  • Monash University
  • Oregon State University
  • Rhodes University
  • German Center for Integrative Biodiversity Research
  • Charles University
  • African Institute for Mathematical Sciences