89 research outputs found

    Dated Plant Phylogenies Resolve Neogene Climate and Landscape Evolution in the Cape Floristic Region

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    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 show remarkable consistency across all 12 clades with regard to both the types of environments identified as ancestral, and the timing of shifts to alternative conditions. They reveal that Early Miocene land surfaces of the CFR were wetter than at present and were dominated by quartzitic substrata. These conditions continue to characterize the higher-elevation settings of the Cape Fold Belt, where they have fostered the persistence of ancient fynbos lineages. The Middle Miocene (13-17 Ma) saw the development of perennial to weakly-seasonal arid conditions, with the strongly seasonal rainfall regime of the west coast arising ~6.5-8 Ma. Although the Late Miocene may have seen some exposure of the underlying shale substrata, the present-day substrate diversity of the CFR lowlands was shaped by Pliocene-Pleistocene events. Particularly important was renewed erosion, following the post-African II uplift episode, and the reworking of sediments on the coastal platform as a consequence of marine transgressions and tectonic uplift. These changes facilitated adaptive radiations in some, but not all, lineages studied

    Predicting bat distributions and diversity hotspots in southern Africa

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    Species distribution models were used to predict bat species richness across southern Africa and to identify potential drivers of these spatial patterns. We also identified species richness within each biotic zone and the distributions of species considered of high conservation priority. We used this information to highlight conservation priorities for bats in southern Africa (defined here as between the latitudes of 8° S, slightly north of Zambia, to the southern tip of Africa 34° S, an area of approximately 9781840 km2). We used maximum entropy modelling (Maxent) to model habitat suitability for 58 bat species in order to determine the key eco-geographical variables influencing their distributions. The potential distribution of each bat species was affected by different ecogeographic variables but in general, water availability (both temporary and permanent), seasonal precipitation, vegetation, and karst (caves/limestone) areas were the most important factors. The highest levels of species richness were found mainly in the eastern dry savanna area and some areas of wet savanna. Of the species considered to be of high priority due to a combination of restricted distributions or niches and/or endemism (7 fruit bats, 23 cave-dwellers, 18 endemic and near-endemic, 14 niche-restricted and 15 range-restricted), nine species were considered to be at most risk. We found that range-restricted species were commonly found in areas with low species richness; therefore, conservation decisions need to take into account not only species richness but also species considered to be particularly vulnerable across the biogeographical area of interestinfo:eu-repo/semantics/publishedVersio

    Genomic Fingerprints of Palaeogeographic History: The Tempo and Mode of Rift Tectonics Across Tropical Africa Has Shaped the Diversification of the Killifish Genus Nothobranchius (Teleostei: Cyprinodontiformes)

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    This paper reports a phylogeny of the African killifishes (Genus Nothobranchius, Order Cyprinodontiformes) informed by five genetic markers (three nuclear, two mitochondrial) of 80 taxa (seven undescribed and 73 of the 92 recognized species). These short-lived annual fishes occupy seasonally wet habitats in central and eastern Africa, and their distribution coincides largely with the East African Rift System (EARS). The fossil dates of sister clades used to constrain a chronometric tree of all sampled Nothobranchius recovered the origin of the genus at ~13.27 Mya. It was followed by the radiations of six principal clades through the Neogene. An ancestral area estimation tested competing biogeographical hypotheses to constrain the ancestral origin of the genus to the Nilo-Sudan Ecoregion, which seeded a mid-Miocene dispersal event into the Coastal ecoregion, followed closely (~10 Mya) by dispersals southward across the Mozambique coastal plain into the Limpopo Ecoregion. Extending westwards across the Tanzanian plateau, a pulse of radiations through the Pliocene were associated with dispersals and fragmentation of wetlands across the Kalahari and Uganda Ecoregions. We interpret this congruence of drainage rearrangements with dispersals and cladogenic events of Nothobranchius to reflect congruent responses to recurrent uplift and rifting. The coevolution of these freshwater fishes and wetlands is attributed to ultimate control by tectonics, as the EARS extended southwards during the Neogene. Geobiological consilience of the combined evidence supports a tectonic hypothesis for the evolution of Nothobranchius

    Phylogeography and cryptic diversity of the solitary-dwelling silvery mole-rat, genus Heliophobius (family: Bathyergidae)

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    Alongside the eusocial naked mole-rat, Heterocephalus glaber, Heliophobius argenteocinereus represents the second oldest lineage within the African mole-rat family Bathyergidae, and phylogenetically intermediate between the East African Het. glaber and the South African genera Bathyergus and Georychus. Across its geographic range, Hel.. argenteocinereus is widely distributed on both sides of the East African Rift System (EARS), and is a key taxon for understanding the phylogeographic patterns of divergence of the family as a whole. Phylogenetic analysis of 62 mitochondrial cyt b sequences, representing 48 distinct haplotypes from 26 geographic locations across the range of Heliophobius, consistently and robustly resolved six genetically divergent clades that we recognize as distinct evolutionary species. Early species descriptions of Heliophobius were synonymized into a monotypic taxonomy that recognized only Hel. argentocinereus. These synonyms constitute available names for these rediscovered cryptic lineages, for which combined morphological and genetic evidence for topotypical populations endorses the recognition of six to eight distinct taxa. Bayesian estimates of diver- gence times using the fossil Proheliophobius as a calibration for the molecular clock suggest that the adaptive radiation of the genus began in the early Miocene, and that cladogenesis, represented in the extant species, reflects a strident signa- ture of tectonic activity that forged the principal graben in the EARS.SYNTHESYS grant (BE-TAF-289), grants from the National Research Foundation, the University of Pretoria South Africa (to NCB) and the ERANDA and Bay Foundations (FC).http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1469-7998ab201

    Experience of an NIHR Clinical Lectureship (medical/dental) and the determining factors for a clinical academic career post lectureship:a mixed-method evaluation

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    Objectives: The objective of this study is to investigate early-to-late postdoctoral clinical academic progression and the experiences of NIHR Clinical Lectureship (CL) fellows, considering enablers and barriers to success, and identifying the factors associated with immediate progression to a clinical academic role following completion of the award. Setting: Datasets of CL awardees across the UK. Participants: For semistructured interviews, n=40 CL awardees that had finished their award within the previous 5 years. For quantitative analysis, n=1226 completed or currently active CL awardees. Outcome measures: The responses from the semistructured interviews to the defined questions on experiences during the award, postaward progression, and enablers and barriers to academic progression. Other primary outcome measures were quantitative data on first destinations postaward, demographic data, and whether an awardee had previously held an NIHR Academic Clinical Fellowship (ACF) or was a recipient of the Academy of Medical Sciences (AMS) Starter Grant. Results: CL awardees identified numerous benefits to the award, with the majority achieving their aims. Most awardees progressed to a clinical academic role; however, some returned to a clinical only position, citing concerns around the time pressure associated with balancing clinical and academic responsibilities, and the competition to attain further postdoctoral awards. The region of the award partnership, year of award end and success in applying for an AMS Starter Grant were associated with progression to a clinical academic role. Gender, holding an ACF and having a craft or non-craft specialty had no independent statistical association with clinical academic progression. Conclusions: The CL is a valued element of the Integrated Academic Pathway. By addressing issues around later postdoctoral progression opportunities, responding to challenges experienced by CLs, and by understanding the factors identified in this study associated with clinical academic progression, it should be possible to increase the proportion of CLs that become fully independent clinical academic research leaders. Participants: 1226 NIHR CLs active or completed on the award between 2006 and 2020

    Cryptic Diversity of African Tigerfish (Genus Hydrocynus) Reveals Palaeogeographic Signatures of Linked Neogene Geotectonic Events

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    The geobiotic history of landscapes can exhibit controls by tectonics over biotic evolution. This causal relationship positions ecologically specialized species as biotic indicators to decipher details of landscape evolution. Phylogeographic statistics that reconstruct spatio-temporal details of evolutionary histories of aquatic species, including fishes, can reveal key events of drainage evolution, notably where geochronological resolution is insufficient. Where geochronological resolution is insufficient, phylogeographic statistics that reconstruct spatio-temporal details of evolutionary histories of aquatic species, notably fishes, can reveal key events of drainage evolution. This study evaluates paleo-environmental causes of mitochondrial DNA (mtDNA) based phylogeographic records of tigerfishes, genus Hydrocynus, in order to reconstruct their evolutionary history in relation to landscape evolution across Africa. Strong geographical structuring in a cytochrome b (cyt-b) gene phylogeny confirms the established morphological diversity of Hydrocynus and reveals the existence of five previously unknown lineages, with Hydrocynus tanzaniae sister to a clade comprising three previously unknown lineages (Groups B, C and D) and H. vittatus. The dated phylogeny constrains the principal cladogenic events that have structured Hydrocynus diversity from the late Miocene to the Plio-Pleistocene (ca. 0–16 Ma). Phylogeographic tests reveal that the diversity and distribution of Hydrocynus reflects a complex history of vicariance and dispersals, whereby range expansions in particular species testify to changes to drainage basins. Principal divergence events in Hydrocynus have interfaced closely with evolving drainage systems across tropical Africa. Tigerfish evolution is attributed to dominant control by pulses of geotectonism across the African plate. Phylogenetic relationships and divergence estimates among the ten mtDNA lineages illustrates where and when local tectonic events modified Africa's Neogene drainage. Haplotypes shared amongst extant Hydrocynus populations across northern Africa testify to recent dispersals that were facilitated by late Neogene connections across the Nilo-Sahelian drainage. These events in tigerfish evolution concur broadly with available geological evidence and reveal prominent control by the African Rift System, evident in the formative events archived in phylogeographic records of tigerfish

    Correlated Genetic and Ecological Diversification in a Widespread Southern African Horseshoe Bat

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    The analysis of molecular data within a historical biogeographical framework, coupled with ecological characteristics can provide insight into the processes driving diversification. Here we assess the genetic and ecological diversity within a widespread horseshoe bat Rhinolophus clivosus sensu lato with specific emphasis on the southern African representatives which, although not currently recognized, were previously described as a separate species R. geoffroyi comprising four subspecies. Sequence divergence estimates of the mtDNA control region show that the southern African representatives of R. clivosus s.l. are as distinct from samples further north in Africa than they are from R. ferrumequinum, the sister-species to R. clivosus. Within South Africa, five genetically supported geographic groups exist and these groups are corroborated by echolocation and wing morphology data. The groups loosely correspond to the distributions of the previously defined subspecies and Maxent modelling shows a strong correlation between the detected groups and ecoregions. Based on molecular clock calibrations, it is evident that climatic cycling and related vegetation changes during the Quaternary may have facilitated diversification both genetically and ecologically

    Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

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    The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

    Dimethyl fumarate in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial

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    Dimethyl fumarate (DMF) inhibits inflammasome-mediated inflammation and has been proposed as a treatment for patients hospitalised with COVID-19. This randomised, controlled, open-label platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]), is assessing multiple treatments in patients hospitalised for COVID-19 (NCT04381936, ISRCTN50189673). In this assessment of DMF performed at 27 UK hospitals, adults were randomly allocated (1:1) to either usual standard of care alone or usual standard of care plus DMF. The primary outcome was clinical status on day 5 measured on a seven-point ordinal scale. Secondary outcomes were time to sustained improvement in clinical status, time to discharge, day 5 peripheral blood oxygenation, day 5 C-reactive protein, and improvement in day 10 clinical status. Between 2 March 2021 and 18 November 2021, 713 patients were enroled in the DMF evaluation, of whom 356 were randomly allocated to receive usual care plus DMF, and 357 to usual care alone. 95% of patients received corticosteroids as part of routine care. There was no evidence of a beneficial effect of DMF on clinical status at day 5 (common odds ratio of unfavourable outcome 1.12; 95% CI 0.86-1.47; p = 0.40). There was no significant effect of DMF on any secondary outcome

    Dimethyl fumarate in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial

    Get PDF
    Dimethyl fumarate (DMF) inhibits inflammasome-mediated inflammation and has been proposed as a treatment for patients hospitalised with COVID-19. This randomised, controlled, open-label platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]), is assessing multiple treatments in patients hospitalised for COVID-19 (NCT04381936, ISRCTN50189673). In this assessment of DMF performed at 27 UK hospitals, adults were randomly allocated (1:1) to either usual standard of care alone or usual standard of care plus DMF. The primary outcome was clinical status on day 5 measured on a seven-point ordinal scale. Secondary outcomes were time to sustained improvement in clinical status, time to discharge, day 5 peripheral blood oxygenation, day 5 C-reactive protein, and improvement in day 10 clinical status. Between 2 March 2021 and 18 November 2021, 713 patients were enroled in the DMF evaluation, of whom 356 were randomly allocated to receive usual care plus DMF, and 357 to usual care alone. 95% of patients received corticosteroids as part of routine care. There was no evidence of a beneficial effect of DMF on clinical status at day 5 (common odds ratio of unfavourable outcome 1.12; 95% CI 0.86-1.47; p = 0.40). There was no significant effect of DMF on any secondary outcome
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