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Feeding ecology and interactions with mammal hosts in a symbiotic genus of birds ( Buphagus spp.) in Namibia

AVIAN RESEARCH 2024年第3期15卷 336-344页

作者： Lukubwe, Michael S. Velarde-Garcez, Daniel Sequeira, Fernando Lopes, Susana Craig, Adrian J. F. K. Mata, Vanessa A. rhodes univ Dept Zool & Entomol Makhanda South Africa univ Namibia Dept Wildlife Management & Tourism Studies Katima Mulilo Campus Windhoek Namibia univ Porto Fac Ciencias Dept Biol Porto Portugal Ctr Invest Biodiversidade & Recursos Genet InBIO Lab Associado CIBIO Campus Vairao Vairao Portugal CIBIO BIOPOLIS Program Genom Biodivers & Land Planning Campus Vairao Vairao Portugal

As the sole obligate symbiotic birds in Africa, oxpeckers offer a unique model for studying symbiotic relationships. Due to the multitrophic level they occupy and the context dependent foraging behavior they exhibit, the type of symbiotic relationship can be variable. In addition to providing a cleaning service to the host by removing ticks, oxpeckers frequently feed on blood, mucus, and saliva, inflicting potential damage on the host. Here, we used DNA metabarcoding on faecal samples to analyze the taxonomic composition of the trophic interactions of the Yellow-billed Oxpecker ( Buphagus africanus) ) and Red-billed Oxpecker (B. B . erythrorhynchus) ) in northeastern Namibia. In contrast to conventional methods, DNA metabarcoding allows for a detailed identification of dietary resources encompassing both mammal hosts and consumed arthropods within the same samples. With this information, we examined differences in the diet composition between oxpecker species and localities, as well as the co-occurrence between host and arthropod species. Our findings revealed that oxpeckers predominantly source their diet from mammals, ticks, and flies; however, ticks and flies rarely co-occur in the diet of an individual. We observed variability among individuals in their feeding ecology, which is strongly correlated with locality and, to a lesser extent, with the mammal host. We noted a high degree of mobility between hosts within relatively short periods, with 32% of the samples showing traces of at least two mammal hosts. This study illustrates the dynamic foraging behavior of these specialized symbiotic birds, shedding light on their potential role in pest control services and disease transmission.

关键词： Commensalism Diet DNA metabarcoding Oxpeckers Parasitism Trophic ecology RED-BILLED OXPECKER NATIONAL-PARK PREFERENCES ERYTHRORHYNCHUS MUTUALISM BEHAVIOR PARASITISM TICKS

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Photosynthetic response to a winter heatwave in leading and trailing edge populations of the intertidal red alga Corallina officinalis (Rhodophyta)

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ACTA OCEANOLOGICA SINICA 2024年第7期43卷 70-77页

作者： Kolzenburg, Regina Ragazzola, Federica Tamburello, Laura Nicastro, Katy R. Mcquaid, Christopher D. Zardi, Gerardo I. Umea univ Umea Marine Sci Ctr S-90571 Norrbyn Sweden univ Portsmouth Inst Marine Sci Portsmouth PO49LY England Genova Marine Ctr Stn Zool Anton Dohrn I-16126 Genoa Italy Sicily Marine Ctr Stn Zool Anton Dohrn I-90149 Palermo Italy rhodes univ Dept Zool & Entomol ZA-6139 Makhanda South Africa univ Algarve Ctr Marine Sci P-8005139 Faro Portugal univ Lille Lab Oceanol & Geosci F-59000 Lille France univ Caen Normandie Lab Biol Organismes & Ecosyst Aquat F-14032 Caen France

Marine heatwaves (MHWs) caused by anthropogenic climate change are becoming a key driver of change at the ecosystem level. Thermal conditions experienced by marine organisms across their distribution, particularly towards the equator, are likely to approach their physiological limits, resulting in extensive mortality and subsequent changes at the population level. Populations at the margins of their species' distribution are thought to be more sensitive to climate-induced environmental pressures than central populations, but our understanding of variability in fitness-related physiological traits in trailing versus leading-edge populations is limited. In a laboratory simulation study, we tested whether two leading (Iceland) and two trailing (Spain) peripheral populations of the intertidal macroalga Corallina officinalis display different levels of maximum potential quantum efficiency (Fv/Fm) resilience to current and future winter MHWs scenarios. Our study revealed that ongoing and future local winter MHWs will not negatively affect leading-edge populations of C. officinalis, which exhibited stable photosynthetic efficiency throughout the study. Trailing edge populations showed a positive though non-significant trend in photosynthetic efficiency throughout winter MHWs exposure. Poleward and equatorward populations did not produce significantly different results, with winter MHWs having no negative affect on Fv/Fm of either population. Additionally, we found no long-term regional or population-level influence of a winter MHWs on this species' photosynthetic efficiency. Thus, we found no statistically significant difference in thermal stress responses between leading and trailing populations. Nonetheless, C. officinalis showed a trend towards higher stress responses in southern than northern populations. Because responses rest on a variety of local population traits, they are difficult to predict based solely on thermal pressures.

关键词： marginal population coralline algae climate change ecophysiology photophysiology macroalgae Fv/Fm TEMPERATURE TOLERANCE THERMAL LIMITS CLIMATE-CHANGE ACCLIMATION ADAPTATION PATTERNS BIODIVERSITY BIOGEOGRAPHY EVOLUTION ECOLOGY

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Feeding ecology and interactions with mammal hosts in a symbiotic genus of birds(Buphagus spp.) in Namibia

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Avian Research 2024年第3期 336-344页

作者： Michael S.Lukubwe Daniel Velarde-Garcéz Fernando Sequeira Susana Lopes Adrian J.F.K.Craig Vanessa A.Mata Department of Zoology and Entomology Rhodes University Department of Wildlife Management and Tourism Studies University of Namibia Departamento de Biologia Faculdade de CiênciasUniversidade do Porto CIBIO Centro de Investiga??o em Biodiversidade e Recursos Genéticos In BIO Laboratório AssociadoCampus de Vair?o BIOPOLIS Program in Genomics Biodiversity and Land Planning CIBIOCampus de Vair?o

As the sole obligate symbiotic birds in Africa, oxpeckers offer a unique model for studying symbiotic relationships. Due to the multitrophic level they occupy and the context dependent foraging behavior they exhibit, the type of symbiotic relationship can be variable. In addition to providing a cleaning service to the host by removing ticks, oxpeckers frequently feed on blood, mucus, and saliva, inflicting potential damage on the host. Here, we used DNA metabarcoding on faecal samples to analyze the taxonomic composition of the trophic interactions of the Yellow-billed Oxpecker(Buphagus africanus) and Red-billed Oxpecker(B. erythrorhynchus) in northeastern Namibia. In contrast to conventional methods, DNA metabarcoding allows for a detailed identification of dietary resources encompassing both mammal hosts and consumed arthropods within the same samples. With this information, we examined differences in the diet composition between oxpecker species and localities, as well as the co-occurrence between host and arthropod species. Our findings revealed that oxpeckers predominantly source their diet from mammals, ticks, and flies; however, ticks and flies rarely co-occur in the diet of an individual. We observed variability among individuals in their feeding ecology, which is strongly correlated with locality and, to a lesser extent, with the mammal host. We noted a high degree of mobility between hosts within relatively short periods, with 32% of the samples showing traces of at least two mammal hosts. This study illustrates the dynamic foraging behavior of these specialized symbiotic birds, shedding light on their potential role in pest control services and disease transmission.

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Assessment of the performance of the TOPGNSS and ANN-MB antennas for ionospheric measurements using low-cost u-blox GNSS receivers

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Geodesy and Geodynamics 2024年第3期15卷 291-301页

作者： Daniel Okoh Aderonke Obafaye Oluwakemi Dare-Idowu Babatunde Rabiu Anton Kashcheyev Claudio Cesaroni John Bosco Habarulema Bruno Nava United Nations African Regional Centre for Space Science and Technology Education-English(UN-ARCSSTE-E) Obafemi Awolowo University CampusIle IfeNigeria National Institute for Geophysics and Volcanology(INGV) 00143 RomeItaly Institute for Space Science and Engineering African University of Science and TechnologyAbujaNigeria university of New Brunswick FrederictonCanada South African National Space Agency(SANSA) P.O Box 32Hermanus 7200South Africa Department of Physics and Electronics Rhodes University6140 MakhandaSouth Africa The Abdus Salam International Centre for Theoretical Physics Strada Costiera11I-34151 TriesteItaly

Low-cost GNSS receivers have recently been gaining reliability as good candidates for ionospheric studies. In line with these gains are genuine concerns about improving the performance of these receivers. In this work, we present a comprehensive investigation of the performances of two antennas(the u-blox ANN-MB and the TOPGNSS TOP-106) used on a low-cost GNSS receiver known as the u-blox ZED-F9P. The two antennas were installed on two identical and co-located u-blox receivers. Data used from both receivers cover the period from January to June 2022. Results from the study indicate that the signal strengths are dominantly greater for the receiver with the TOPGNSS antenna than for the receiver with the ANN-MB antenna, implying that the TOPGNSS antenna is better than the ANN-MB antenna in terms of providing greater signal strengths. Summarily, the TOPGNSS antenna also performed better in minimizing the occurrence of cycle slips on phase TEC measurements. There are no conspicuous differences between the variances(computed as 5-min standard deviations) of phase TEC measurements for the two antennas, except for a period around May-June when the TOPGNSS gave a better performance in terms of minimizing the variances in phase TEC. Remarkably, the ANN-MB antenna gave a better performance than the TOPGNSS antenna in terms of minimizing the variances in pseudorange TEC for some satellite observations. For precise horizontal(North and East) positioning, the receiver with the TOPGNSS antenna gave better results, while the receiver with the ANN-MB antenna gave better vertical(Up) positioning. The errors for the receivers of both antennas are typically within about 5 m(the monthly mean was usually smaller than 1 m) in the horizontal direction and within about 10 m(the monthly mean was usually smaller than 4 m) in the vertical direction.

关键词： GNSS Ionosphere Low-cost Antenna TOPGNSS U-blox

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Photosynthetic response to a winter heatwave in leading and trailing edge populations of the intertidal red alga Corallina officinalis(Rhodophyta)

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Acta Oceanologica Sinica 2024年第07期 70-77页

作者： Regina Kolzenburg Federica Ragazzola Laura Tamburello Katy R.Nicastro Christopher D.McQuaid Gerardo I.Zardi Ume? Marine Sciences Centre Ume? University university of Portsmouth Institute of Marine Science Stazione Zoologica Anton Dohrn Genova Marine Center Stazione Zoologica Anton Dohrn Sicily Marine Center Department of Zoology and Entomology Rhodes University Centre of Marine Sciences University of Algarve Laboratoire d'Océanologie et de Géosciences Université de Lille université de Caen Normandie Laboratoire de Biologie des Organismes et des Ecosystèmes Aquatiques

Marine heatwaves(MHWs) caused by anthropogenic climate change are becoming a key driver of change at the ecosystem level. Thermal conditions experienced by marine organisms across their distribution, particularly towards the equator, are likely to approach their physiological limits, resulting in extensive mortality and subsequent changes at the population level. Populations at the margins of their species' distribution are thought to be more sensitive to climate-induced environmental pressures than central populations, but our understanding of variability in fitness-related physiological traits in trailing versus leading-edge populations is limited. In a laboratory simulation study, we tested whether two leading(Iceland) and two trailing(Spain)peripheral populations of the intertidal macroalga Corallina officinalis display different levels of maximum potential quantum efficiency(Fv/Fm) resilience to current and future winter MHWs scenarios. Our study revealed that ongoing and future local winter MHWs will not negatively affect leading-edge populations of C. officinalis,which exhibited stable photosynthetic efficiency throughout the study. Trailing edge populations showed a positive though non-significant trend in photosynthetic efficiency throughout winter MHWs exposure. Poleward and equatorward populations did not produce significantly different results, with winter MHWs having no negative affect on Fv/Fm of either population. Additionally, we found no long-term regional or population-level influence of a winter MHWs on this species' photosynthetic efficiency. Thus, we found no statistically significant difference in thermal stress responses between leading and trailing populations. Nonetheless, C. officinalis showed a trend towards higher stress responses in southern than northern populations. Because responses rest on a variety of local population traits, they are difficult to predict based solely on thermal pressures.

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Isolation and Characterization of SARS-CoV-2 in Kenya

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American Journal of Molecular Biology 2024年第2期14卷 66-83页

作者： Albina Makio Robinson Mugasiali Irekwa Matthew Mutinda Munyao Caroline Wangui Njoroge Peter Kipkemboi Rotich Tonny Teya Nyandwaro Joanne Jepkemei Yego Anne Wanjiru Mwangi James Hungo Kimotho Ronald Tanui Vincent Rutto Samson Muuo Nzou Center for Traditional Medicine and Drug Research Kenya Medical Research Institute Nairobi Kenya Center for Microbiology Research Kenya Medical Research Institute Nairobi Kenya Production Department Kenya Medical Research Institute Nairobi Kenya Department of Biochemistry and Microbiology Rhodes University Grahamstown South Africa Center for Virus Research Kenya Medical Research Institute Nairobi Kenya

The discovery of Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) in Wuhan, Hubei province, China, in December 2019 raised global health warnings. Quickly, in 2020, the virus crossed borders and infected individuals across the world, evolving into the COVID-19 pandemic. Notably, early signs of the virus’s existence were observed in various countries before the initial outbreak in Wuhan. As of 12th of April, the respiratory disease had infected over 762 million people worldwide, with over 6.8 million deaths recorded. This has led scientists to focus their efforts on understanding the virus to develop effective means to diagnose, treat, prevent, and control this pandemic. One of the areas of focus is the isolation of this virus, which plays a crucial role in understanding the viral dynamics in the laboratory. In this study, we report the isolation and detection of locally circulating SARS-CoV-2 in Kenya. The isolates were cultured on Vero Cercopithecus cell line (CCL-81) cells, RNA extraction was conducted from the supernatants, and reverse transcriptase-polymerase chain reaction (RT-PCR). Genome sequencing was done to profile the strains phylogenetically and identify novel and previously reported mutations. Vero CCL-81 cells were able to support the growth of SARS-CoV-2 in vitro, and mutations were detected from the two isolates sequenced (001 and 002). Genome sequencing revealed the circulation of two isolates that share a close relationship with the Benin isolate with the D614G common mutation identified along the S protein. These virus isolates will be expanded and made available to the Kenya Ministry of Health and other research institutions to advance SARS-CoV-2 research in Kenya and the region.

关键词： SARS-CoV-2 COVID-19 Whole Genome Sequencing Phylogenetic Analysis Nucleotide Substitutions Amino Acid Changes

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Comment on “Evidence for Mesoproterozoic collision,deep burial and rapid exhumation of garbenschiefer in the Namaqua Front,South Africa” by Valby Van Schijndel,David ***,Robert Anczkiewicz,Anders Schersten,Geoscience Frontiers,Volume 11,Issue 2,Pag

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Geoscience Frontiers 2020年第5期11卷 1889-1894页

作者： Steffen H.Buttner Department of Geology Rhodes University6139Makhanda(Grahamstown)South Africa

In their recent publication Van Schijndel et al.(2020) present new age data and P-T analysis from the eastern margin of the Namaqua Sector of the Namaqua Natal Metamorphic *** authors claim to provide evidence for the... 详细信息

关键词： Province. burial eastern

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Synthesis and Electronic Structure of A2B Type Halogen Atoms Substituted H3-Triarylcorroles

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Chinese Journal of Structural Chemistry 2017年第3期36卷 367-380页

作者：李敏智朱卫华 MACK John MKHIZE Scebi NYOKONG Tebello 梁旭 School of Chemistry and Chemical Engineering Jiangsu University Department of Chemistry Rhodes University

Seven electron-deficient A_2 B type H_3-triarylcorroles have been synthesized and characterized. The solvent dependence of the electronic absorption and magnetic circular dichroism（MCD） spectra and a series of TD-DFT calculations have been used to analyze trends in the electronic structures. Significant differences are observed in the optical spectra when solvents of differing polarity are used,which can be assigned to the effect of NH-tautomerism.

关键词： A_2B type corrole solvatochromism electronic structure spectroscopy TD-DFT

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Prediction of sediment yield of the Inxu River catchment (South Africa)using the MUSLE

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International Soil and Water Conservation Research 2021年第1期9卷 37-48页

作者： David Gwapedza Namso Nyamela Denis Arthur Hughes Andrew Robert Slaughter Sukhmani Kaur Mantel Benjamin van der Waal Institute for Water Research Rhodes University P.O.Box 94GrahamstownEastern CapeSouth Africa Geography Department Rhodes University P.O.Box 94GrahamstownEastern CapeSouth Africa

The proposed site for the construction of a new dam(Laleni Dam)on the Tsitsa River in the Eastern Cape,South Africa falls within a high soil erosion zone,which is expected to affect the lifespan of the *** the sediment yield of the catchment is important from a management perspective,and thus we designed this study to assess the applicability of the Modified universal Soil Loss Equation(MUSLE).The original MUSLE was applied to the Inxu River sub catchment,upstream of a proposed dam,over a summer rainfall period extending from October 2016 to April 2017.A modified version of the MUSLE,incorporating a storage module,was later applied over the same *** calibration of the MUSLE with and without a storage model was tested against 7 months of recorded daily suspended sediment discharge *** a storage model,we achieved a percentage bias,coefficient of efficiency and R2 of 2%,0.83 and 0.83,respectively,while without storage the performance statistics were markedly *** results suggest that a calibrated MUSLE can provide estimates of sediment yield that are valuable for regional planning,and that the inclusion of a storage component further improves the MUSLE *** the complexity of sediment generation and transport processes,a relatively simple empirical MUSLE model is a useful tool for initial sediment yield estimation for planning purposes.

关键词： MUSLE Storage component Sediment yield Erosion South Africa Inxu river

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Hydration ***:Modelling implications for Fe-Ti oxide crystallisation in mafic intrusions,with specific reference to the Panzhihua intrusion,SW China

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Geoscience Frontiers 2013年第5期4卷 555-569页

作者： Geoffrey H.Howarth Stephen A.Prevec Geology Department Rhodes UniversityP.O.Box 94Grahamstown 6140South Africa

Recent work on the Panzhihua intrusion has produced two separate models for the crystallisation of the intrusion：（1） low-Ti,high CaO and low H2O（0.5 wt.%） parent magma（equivalent to Emeishan low-Ti basalt） at FMQ;and（2） high-Ti,low CaO and higher H2O（＆gt;1.5 wt.%） parent magma（equivalent to Emeishan high-Ti basalt） at FMQ ＋ *** of these parent magma compositions produces significantly different results. We present here detailed f（O2） and H2O modelling for average compositions of both Emeishan high-Ti and low-Ti ferrobasalts in order to constrain the effects on crystallisation sequences for Emeishan ultra-mafic -mafic layered *** is consistent with numerous experimental studies on ferro-basaltic magmas from other localities（*** intrusion）.Modelling is compared with the geology of the Panzhihua intrusion in order to constrain the crystallisation of the gabbroic rocks and the Fe-Ti oxides ore *** suggest that the gabbroic rocks at the Panzhihua intrusion can be best explained by crystallisation from a parent magma similar to that of the high-Ti Emeishan basalt at moderate H2O contents（0.5-1 wt.%） but at the lower end of TiO2 content for typical high-Ti basalts（2.5 wt.%TiO2）. Distinct silicate disequilibrium textures in the Fe-Ti oxide ore layers suggest that an influx of H2O may be responsible for changing the crystallisation *** increase in H2O during crystallisation of gabbroic rocks will result in the depression of silicate liquidus temperatures and resultant disequilibrium with the *** cooling of the magma with high H2O then results in precipitation of Mt-Uv alone. The H2O content of parent magmas for mafic layered intrusions associated with the ELIP is an important variable.H2O alters the crystallisation sequence of the basaltic magmas so that at high H2O and f（O2） Mt -Uv crystallises earlier than plagioclase and ***,the addition of H2O to an anhydrous magma can explain silicate dis

关键词： f(O2) H2O Panzhihua Parent magma Fe-Ti oxide ore Petrogenesis

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