Now showing items 21-40 of 816

    • Insights into the red algae and eukaryotic evolution from the genome of Porphyra umbilicalis (Bangiophyceae, Rhodophyta)

      Brawley, SH; Blouin, NA; Ficko-Blean, E; Wheeler, GL; Lohr, M; Goodson, HV; Jenkins, JW; Blaby-Haas, CE; Helliwell, KE; Chan, CX; et al. (National Academy of Sciences, 2017-08-01)
      Porphyra umbilicalis (laver) belongs to an ancient group of red algae (Bangiophyceae), is harvested for human food, and thrives in the harsh conditions of the upper intertidal zone. Here we present the 87.7-Mbp haploid Porphyra genome (65.8% G + C content, 13,125 gene loci) and elucidate traits that inform our understanding of the biology of red algae as one of the few multicellular eukaryotic lineages. Novel features of the Porphyra genome shared by other red algae relate to the cytoskeleton, calcium signaling, the cell cycle, and stress-tolerance mechanisms including photoprotection. Cytoskeletal motor proteins in Porphyra are restricted to a small set of kinesins that appear to be the only universal cytoskeletal motors within the red algae. Dynein motors are absent, and most red algae, including Porphyra, lack myosin. This surprisingly minimal cytoskeleton offers a potential explanation for why red algal cells and multicellular structures are more limited in size than in most multicellular lineages. Additional discoveries further relating to the stress tolerance of bangiophytes include ancestral enzymes for sulfation of the hydrophilic galactan-rich cell wall, evidence for mannan synthesis that originated before the divergence of green and red algae, and a high capacity for nutrient uptake. Our analyses provide a comprehensive understanding of the red algae, which are both commercially important and have played a major role in the evolution of other algal groups through secondary endosymbioses.
    • Building Bridges. Response to Erkens and Hoorn: “The Panama Isthmus, ‘old’, ‘young’ or both?”.

      O'Dea, A; Aguilera, O; Aubry, M-P; Berggren, WA; Budd, AF; Cione, AL; Coates, AG; Collins, LS; Coppard, SE; Cozzuol, MA; et al. (American Association for the Advancement of Science: Science Advances, 2016-08-17)
    • Crookesite, Cu7TlSe4, from Littleham Cove, Devon: the first mineral containing essential thallium from the British Isles

      Rumsey, MS; Dossett, I; Green, DI; Najorka, J; Spratt, J; Rumsey, MS (The Russell Society, 2015-10-01)
      The rare thallium copper selenide crookesite occurs as dark grey metallic needles in at least two cavities in a nodule collected from cliffs at Littleham Cove, Budleigh Salterton, Devon. This is the first report of a thallium mineral from the British Isles. The small crystal size, confusion in the mineralogical literature and the need to preserve as much of the specimen as possible for future study, made the identification particularly challenging. Thallium minerals have a very limited worldwide distribution. They are almost entirely restricted to unusual low temperature epithermal deposits. The discovery of crookesite in nodules in a Permian red bed environment is, therefore of significant interest. Thallium minerals do not appear to have been reported in this geological setting before.
    • Hydroxyferroroméite, a new secondary weathering mineral from Oms, France

      Mills, S; Christy, A; Rumsey, M; Spratt, J; Bittarello, E; Favreau, G; Ciriotti, M; Berbain, C (2017-04-28)
      Hydroxyferroroméite, ideally (Fe2+ 1.5[]0.5)Sb5+ 2O6(OH), is a new secondary mineral from the Correc d'en Llinassos, Oms, Pyrénées-Orientales Department, France. Hydroxyferroroméite occurs as yellow to yellow-brown powdery boxwork replacements up to about 50μm across after tetrahedrite in a siderite–quartz matrix. No distinct crystals have been observed. The empirical formula (based on 7 (O + OH) per formula unit, pfu) is (Fe2+ 1.07Cu2+ 0.50Zn0.03Sr0.03Ca 0.01[]0.36)Σ2 (Sb5+ 1.88Si0.09Al0.02As0.01)Σ2 O6 ((OH)0.86 O0.14). X-ray photoelectron spectroscopy was used to determine the valence states of Sb, Fe and Cu. Hydroxyferroroméite crystallises in the space group Fd3 m with the pyrochlore structure and hence is a new Fe2+ -dominant member of the roméite group of the pyrochlore supergroup. It has the unit-cell parameters: a = 10.25(3) Å, V = 1077(6) Å3 and Z = 8. A model, based on bond-valence theory, for incorporation of the small Fe2+ cation into a displaced variant of the A site of the pyrochlore structure is proposed.
    • Conservation in a Barcode Age: A cross-discipline re-storage project for pyritic specimens

      Allington-Jones, L; Trafford, A (International Council of Museums, 2017-01-01)
      The dichotomy of conservation and access has long been recognised within the museum profession. The recent push for digitisation has added a new dimension to this argument: digital records can both increase potential access, due to increased awareness of the existence of objects, and decrease potential handling, since a more thorough awareness of an object creates a more informed decision regarding whether access is actually necessary. The use of barcodes and the creation of digital resources have therefore been incorporated into a re-storage project at the Natural History Museum, London to reduce duplication of work (and handling) by staff and to combat the reduction in access caused by the enclosure of objects within microenvironments, which in turn helps preserve specimens for future access. This project demonstrates how conservation and digitisation can successfully synthesise through the use of barcodes, when working with a cross-discipline team.
    • The Airless Project

      Allington-Jones, L; Trafford, A (Natural Sciences Collections Association, 2017-04-20)
      A project to combat pyrite oxidation at the NHM (London, UK) is currently in its second year. The project aims to undertake conservation treatments and store highest risk specimens in low oxygen microenvironments. An emergent benefit of the conservation-driven project has been the digitisation of specimens on the collection management system KE Emu, through the use of barcodes and web-based applications.
    • Lycopodiella inundata: insights into plant-fungal associations in early vascular plants

      Kowal, J; Duckett, J; Jacob, A; Rimington, W; Bidartondo, M; Field, K; Schornack, S; Pressel, S (2017-03-07)
      Recent studies have revealed that extant basal vascular plants associate with a wide range of Mucoromycotina and/or Glomeromycota fungi, paralleling the same in non-vascular liverworts and hornworts. This dispels the long-held paradigm that these early diverging lineages harbour Glomeromycota exclusively. Endophytes belonging to both fungal lineages have also been reported, for the first time, in a Devonian plant (Horneophyton ligneri). Together these discoveries point to much more diverse plant-fungus interactions in early vascular plants than previously assumed, however our understanding of these remains limited. In order to gain further insights into these key partnerships, especially those involving the early diverging Mucoromycotina, we are developing the lycophyte Lycopodiella inundata as an experimental system. L. inundata sporophytes have been shown to harbour solely Mucoromycotina fungi but equally fundamental, the identity of its gametophyte endophyte remains unknown. Using molecular and cytological approaches, we confirm that young L. inundata sporophytes are colonized exclusively by Mucoromycotina and show that the cytology of colonisation - consisting of both inter- and intracellular phases - closely resembles that in Haplomitriopsida liverwort-Mucoromycotina partnerships and the corm of H. ligneri. Our current isolation, resynthesis and molecular studies will provide further insights into both host and fungi specificity.
    • Cladistics

      Kitching, I; Forey, PL; Williams, DM (Elsevier, 2017-01-01)
      Cladistics is a class of methods of biological classification that groups taxa hierarchically into discrete sets and subsets. This article presents the principles and concepts of cladistics and describes the principal analytical methods. The operations by which observations of organisms are coded for analysis are explained, followed by the methods for reconstructing the hierarchical relationships among taxa (usually expressed as branching diagrams termed cladograms). Statistics and principles for determining the degree of fit between data and cladograms are discussed, which permit choices to be made among competing cladograms.
    • Porphyry indicator minerals and their mineral chemistry as vectoring and fertility tools

      Wilkinson, JJ; Cooke, DR; Baker, MJ; Chang, Z; Wilkinson, CC; Chen, H; Fox, N; Hollings, P; White, NC; Gemmell, JB; et al. (Geological Survey of CanadaOttawa, 2017-12-21)
    • Cyclophyllidea van Beneden in Braun, 1900

      Mariaux, J; Tkach, VV; Vasileva, GP; Waeschenbach, A; Beveridge, I; Dimitrova, Y; Haukisalmi, V; Greiman, SE; Littlewood, DT; Makarikov, AA; et al. (The KU Natural History MuseumLawrence, Kansas, 2017-07-20)
    • Thermodynamic controls on element partitioning between titanomagnetite and andesitic–dacitic silicate melts

      Sievwright, RH; Wilkinson, JJ; O'Neill, HSC; Berry, AJ (SpringerLink, 2017-07-07)
      Titanomagnetite–melt partitioning of Mg, Mn, Al, Ti, Sc, V, Co, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Hf and Ta was investigated experimentally as a function of oxygen fugacity (fO2) and temperature (T) in an andesitic–dacitic bulk-chemical compositional range. In these bulk systems, at constant T, there are strong increases in the titanomagnetite–melt partitioning of the divalent cations (Mg2+, Mn2+, Co2+, Ni2+, Zn2+) and Cu2+/Cu+ with increasing fO2 between 0.2 and 3.7 log units above the fayalite–magnetite–quartz buffer. This is attributed to a coupling between magnetite crystallisation and melt composition. Although melt structure has been invoked to explain the patterns of mineral–melt partitioning of divalent cations, a more rigorous justification of magnetite–melt partitioning can be derived from thermodynamic principles, which accounts for much of the supposed influence ascribed to melt structure. The presence of magnetite-rich spinel in equilibrium with melt over a range of fO2 implies a reciprocal relationship between a(Fe2+O) and a(Fe3+O1.5) in the melt. We show that this relationship accounts for the observed dependence of titanomagnetite–melt partitioning of divalent cations with fO2 in magnetite-rich spinel. As a result of this, titanomagnetite–melt partitioning of divalent cations is indirectly sensitive to changes in fO2 in silicic, but less so in mafic bulk systems.
    • Marine hotspots of activity inform protection of a threatened community of pelagic species in a large oceanic jurisdiction

      Requena, S; Oppel, S; Bond, AL; Hall, J; Cleeland, J; Crawford, RJM; Davies, D; Dilley, BJ; Glass, T; Makhado, A; et al. (Wiley, 2020-03-25)
      Remote oceanic islands harbour unique biodiversity, especially of species that rely on the marine trophic resources around their breeding islands. Identifying marine areas used by such species is essential to manage and limit processes that threaten these species. The Tristan da Cunha territory in the South Atlantic Ocean hosts several endemic and globally threatened seabirds, and pinnipeds; how they use the waters surrounding the islands must be considered when planning commercial activities. To inform marine management in the Tristan da Cunha Exclusive Economic Zone (EEZ), we identified statistically significant areas of concentrated activity by collating animal tracking data from nine seabirds and one marine mammal. We first calculated the time that breeding adults of the tracked species spent in 10 × 10 km cells within the EEZ, for each of four seasons to account for temporal variability in space use. By applying a spatial aggregation statistic over these grids for each season, we detected areas that are used more than expected by chance. Most of the activity hotspots were either within 100 km of breeding colonies or were associated with seamounts, being spatially constant across several seasons. Our simple and effective approach highlights important areas for pelagic biodiversity that will benefit conservation planning and marine management strategies.
    • Distributional Patterns of Polychaetes Across the West Antarctic Based on DNA Barcoding and Particle Tracking Analyses

      Brasier, MJ; Harle, J; Wiklund, H; Jeffreys, RM; Linse, K; Ruhl, HA; Glover, AG (2017-11-16)
      Recent genetic investigations have uncovered a high proportion of cryptic species within Antarctic polychaetes. It is likely that these evolved in isolation during periods of glaciation, and it is possible that cryptic populations would have remained geographically restricted from one another occupying different regions of Antarctica. By analysing the distributions of nine morphospecies, (six of which contained potential cryptic species), we find evidence for widespread distributions within the West Antarctic. Around 60% of the cryptic species exhibited sympatric distributions, and at least one cryptic clade was found to be widespread. Additional DNA barcodes from GenBank and morphological records extended the observed range of three species studied here, and indicate potential circum-Antarctic traits. Particle tracking analyses were used to model theoretical dispersal ranges of pelagic larvae. Data from these models suggest that the observed species distributions inferred from genetic similarity could have been established and maintained through the regional oceanographic currents, including the Antarctic Circumpolar Current (ACC) and its coastal counter current. Improved understanding of the distribution of Antarctic fauna is essential for predicting the impacts of environmental change and determining management strategies for the region.
    • Identification Trainers for the Future: Bridging the skills gap in natural history

      West, SVL (Linnean Society, 2017-09-07)
      The Identification Trainers for the Future project has been a 3-year project developing a new model of species identification training for the Museum, while also looking at sector-related career issues, particularly methods of recruitment from non-traditional entry routes into the UK biodiversity and museums sectors. Through funding from the HLF’s Skills for the Future programme and working in partnership with the NBNT and FSC, 15 trainees have worked through 12-month long work-based traineeships with us, developing their technical skills in species identification for cryptic UK taxa and developing experience in teaching and scientific communication. This talk will look at some of the lessons learnt from the project, as well as discussing some of the ways forward for the Museum now the project is starting to draw to a close.
    • Bridging the Skills Gap in UK Species Identification: Lessons Learnt & Next Steps

      West, SVL; Tweddle, JC (National Biodiversity Network, 2017-11-17)
      As the Identification Trainers for the Future project draws to a close, we take this opportunity to reflect on what we have learnt from the project and where the Natural History Museum is heading next in terms of supporting UK natural history skills development.
    • Mapping freshwater snails in north-western Angola: distribution, identity and molecular diversity of medically important taxa

      Allan, F; Sousa-Figueiredo, JC; Emery, AM; Paulo, R; Mirante, C; Sebastião, A; Brito, M; Rollinson, D (BMC & Springer Nature, 2017-10-10)
      This study was designed to determine the distribution and identity of potential intermediate snail hosts of Schistosoma spp. in Bengo, Luanda, Kwanza Norte and Malanje Provinces in north-western Angola. This is an area where infection with Schistosoma haematobium, causing urogenital schistosomiasis, is common but little is yet known about transmission of the disease. Angola has had a varied past with regard to disease control and is revitalising efforts to combat neglected tropical diseases.
    • Sequestration of Martian CO2 by mineral carbonation

      Tomkinson, T; Lee, MR; Mark, DF; Smith, CL (Springer Science and Business Media LLC, 2013-10-22)
      Carbonation is the water-mediated replacement of silicate minerals, such as olivine, by carbonate, and is commonplace in the Earth’s crust. This reaction can remove significant quantities of CO2 from the atmosphere and store it over geological timescales. Here we present the first direct evidence for CO2 sequestration and storage on Mars by mineral carbonation. Electron beam imaging and analysis show that olivine and a plagioclase feldspar-rich mesostasis in the Lafayette meteorite have been replaced by carbonate. The susceptibility of olivine to replacement was enhanced by the presence of smectite veins along which CO2-rich fluids gained access to grain interiors. Lafayette was partially carbonated during the Amazonian, when liquid water was available intermittently and atmospheric CO2 concentrations were close to their present-day values. Earlier in Mars’ history, when the planet had a much thicker atmosphere and an active hydrosphere, carbonation is likely to have been an effective mechanism for sequestration of CO2.
    • Museum archives revisited: Central Asiatic hawkmoths reveal exceptionally high late Pliocene species diversification (Lepidoptera, Sphingidae)

      Hundsdoerfer, AK; Päckert, M; Kehlmaier, C; Strutzenberger, P; Kitching, I (2017-03-14)
      Three high‐elevation Hyles species of Central Asia have proven difficult to sample, and thus, only a limited number of specimens are available for study. Ancient DNA techniques were applied to sequence two mitochondrial genes from ‘historic’ museum specimens of Hyles gallii, Hyles renneri and Hyles salangensis to elucidate the phylogenetic relationships of these species. This approach enabled us to include the holotypes and paratypes. The status of H. salangensis as a species endemic to a mountain range north of Kabul in Afghanistan is confirmed by this study. It is most closely related to Hyles nicaea and H. gallii, and quite distant from the clade comprising the species from Hyles vespertilio to Hyles tithymali, despite this group and H. salangensis both completely lacking an arolium on the pretarsus. Our results show that the samples assigned to H. renneri and Hyles livornica tatsienluica are conspecific and so we reinstate Hyles tatsienluica stat. nov. as the valid name for this species and synonymize H. renneri syn. nov. with it. This study shows that the distribution range postulated for H. tatsienluica extends from Nepal well into the mountains of south‐western China. The distribution ranges of H. livornica and H. tatsienluica overlap. The study confirms the previously proposed synonymies of Hyles nepalensis, Hyles gallii intermedia and Hyles gallii tibetanica with H. gallii. Extensive species sampling (over 80% of Hyles species) in this study allowed additional analyses. The dated phylogeny reveals the global Hyles hawkmoth radiation to be much more recent than previously thought: it began in the Late Miocene and culminated in a Pleistocene burst of diversification in the Northern Hemisphere. Ancestral ranges of basal nodes were reconstructed as highly equivocal, but the Neotropics has the highest probability in the two oldest nodes. Although the origins of the Madagascan and Australian species also remain ambiguous, a large crown clade of fifteen species was reconstructed to have originated in the Palaearctic. The wide distribution ranges of the two migratory species, H. livornica and H. gallii, appear to blur any traces of the biogeographic origin of the clades containing these species. Specialization in larval host plant use onto particular plant families from the ancestral condition ‘polyphagous’ may have led to an increased rate of speciation and phylogenetic diversification in three subgroups of Hyles (the Hawaiian clade, the Hyles centralasiae group and the Hyles euphorbiae complex).
    • A molecular framework for the Cestoda

      Waeschenbach, A; Littlewood, T; Caira, JN; Jensen, K (The KU Natural History MuseumLawrence, Kansas, 2017-07-20)
    • Refining palaeoenvironmental analysis using integrated quantitative granulometry and palynology

      Stukins, S; McIlroy, D; Jolley, DW (The Geological Society, 2017-04-27)
      Accurate palaeoenvironmental analysis is at the heart of producing reliable interpretations and depositional models. This study demonstrates a multivariate statistical approach to facies analysis based on relationships between grain size and quantitative palynology. Our methodology has the advantage that it can be used on small amounts of sample, such as core or well cuttings, as the basis for facies analysis. Proof of concept studies involving the collection of grain-size and palynological datasets from well-exposed outcrops of the Middle Jurassic, Lajas Formation of the Neuquén Basin, Argentina, demonstrate that canonical correspondence analysis can be used to consistently recognize facies and aid in the determination of depositional environments. This study demonstrates the link between depositional facies, grain-size distribution, palynomorph hydrodynamics and assemblage taphonomy of palynomorphs. This knowledge can be transferred into a semi-automated statistical facies prediction technique for the subsurface in complex depositional settings, particularly when calibrated against conventional sedimentary facies analysis.