• Taking the pulse of Mars via dating of a plume-fed volcano

      Cohen, BE; Mark, DF; Cassata, WS; Lee, MR; Tomkinson, T; Smith, CL (2017-12)
    • Taxonomy and phylogeny of mud owls (Annelida: Sternaspidae), including a new synonymy and new records from the Southern Ocean, North East Atlantic Ocean and Pacific Ocean: challenges in morphological delimitation

      Drennan, R; Wiklund, H; Rouse, GW; Georgieva, MN; Wu, X; Kobayashi, G; Yoshino, K; Glover, AG (Springer Science and Business Media LLC, 2019-09-04)
      Species delimitation in sternaspid polychaetes is currently based on the morphology of a limited suite of characters, namely characters of the ventro-caudal shield—a unique feature of the family. Sternaspid species description has increased rapidly in recent years; however, the validity of the shield as a diagnostic character has not been assessed through molecular means. This study performs the largest molecular taxonomy of Sternaspidae to date, using the nuclear gene 18S, and the mitochondrial genes 16S and cytochrome oxidase subunit I (COI) to assess phylogenetic relationships within the family, to reassess the placement of Sternaspidae within the wider polychaete tree and to investigate the effectiveness of the shield as a diagnostic morphological character. This study includes many new records and reports Sternaspis affinis Stimpson, 1864 from USA Pacific coastline and genetic connectivity between specimens identified as Sternaspis cf. annenkovae Salazar-Vallejo & Buzhinskaja, 2013 from off southeastern Australia and specimens identified as Sternaspis cf. williamsae Salazar-Vallejo & Buzhinskaja, 2013 from the northwestern Pacific. In addition, we investigate material identified as Sternaspis cf. scutata (Ranzani, 1817) in the English Channel and compare with S. scutata through both molecular and morphological means. We further perform a detailed morphological and molecular investigation of new sternaspid material collected from the Southern Ocean and Antarctic Peninsula and regard Sternaspis monroi Salazar-Vallejo, 2014 syn. n. as a junior synonym of Sternaspis sendalli Salazar-Vallejo, 2014, two species recently described from the region, raising questions concerning the validity of current morphological delimitation.
    • Taxonomy based on science is necessary for global conservation

      Thomson, SA; Pyle, RL; Ahyong, ST; Alonso-Zarazaga, M; Ammirati, S; Araya, JF; Todd, JA; Barclay, Maxwell; Michel, Ellinor; Nikolaeva, Svetlana; et al. (2018-03-14)
    • Telenomus remus, a Candidate Parasitoid for the Biological Control of Spodoptera frugiperda in Africa, is already Present on the Continent

      Kenis, M; du Plessis, H; Van den Berg, J; Ba, MN; Goergen, G; Kwadjo, KE; Baoua, I; Tefera, T; Buddie, A; Cafa, G; et al. (MDPI, 2019-03-29)
      The fall armyworm, Spodoptera frugiperda, a moth originating from tropical and subtropical America, has recently become a serious pest of cereals in sub-Saharan Africa. Biological control offers an economically and environmentally safer alternative to synthetic insecticides that are being used for the management of this pest. Consequently, various biological control options are being considered, including the introduction of Telenomus remus, the main egg parasitoid of S. frugiperda in the Americas, where it is already used in augmentative biological control programmes. During surveys in South, West, and East Africa, parasitized egg masses of S. frugiperda were collected, and the emerged parasitoids were identified through morphological observations and molecular analyses as T. remus. The presence of T. remus in Africa in at least five countries provides a great opportunity to develop augmentative biological control methods and register the parasitoid against S. frugiperda. Surveys should be carried out throughout Africa to assess the present distribution of T. remus on the continent, and the parasitoid could be re-distributed in the regions where it is absent, following national and international regulations. Classical biological control should focus on the importation of larval parasitoids from the Americas.
    • Temminck's Gallus giganteus; a gigantic obstacle to Darwin's theory of domesticated fowl origin?

      van Grouw, Hein; Dekkers, Wim (British Ornithologists' Club, 2020-09-21)
      In 1813, based on the single foot of a large chicken, Temminck named a ‘new' species of junglefowl, Gallus giganteus. He considered this ‘species’ the ancestor of several large domesticated chicken breeds and believed it was one of six wild ancestral species of domestic fowl. Temminck's hypothesis was rejected by Blyth who thought Red Junglefowl G. gallus was the sole ancestor. The arrival into Britain of several very large Asian chicken breeds in the mid-19th century led to speculation that Temminck's G. giganteus may have been their wild ancestor. Darwin, who had initially agreed with Blyth, noted several peculiarities in the Cochin, a large Asian breed, which he concluded might not have been achieved by selective breeding, and questioned whether G. giganteus was involved in their ancestry. Temminck's giant junglefowl appeared to be a significant hurdle for Darwin in his effort to prove a single ancestral origin for domestic chickens.
    • Tetracapsuloides bryosalmonae abundance in river water

      Fontes, I; Hartikainen, H; Holland, JW; Secombes, CJ; Okamura, B (2017-04-20)
    • Thalhammerite, Pd9Ag2Bi2S4, a New Mineral from the Talnakh and Oktyabrsk Deposits, Noril'sk Region, Russia

      Vymazalova, A; Laufek, F; Sluzhenikin, SF; Kozlov, VV; Stanley, Christopher; Plasil, J; Zaccarini, F; Garuti, G; Bakker, R (2018-08)
    • Thermal metamorphic evolution of the Pułtusk H chondrite breccia – compositional and textural properties not included in petrological classification

      Krzesinska, Agata (2015-12-17)
      The thermal history that chondrites experienced on their parent body is an aspect of their petrological classification. However, in the classification scheme, metamorphic conditions are generally limited to the peak metamorphic temperature attained, while it is known that reconstruction of the genuine thermal evolution of any rock requires identification of various metamorphic factors, definition of the temperature-time path during metamorphism and characterization of the processes responsible for heating. Study of the brecciated Pułtusk H chondrite shows that the meteorite comprises both low and high petrologic type material and should be classified as a H3.8–6 chondrite. Based on the textures and mineral and chemical composition, the thermal metamorphic history of the breccia is reconstructed and it is shown to be inconsistent with the petrologic classification; the textural maturation and degree of compositional equilibrium in the meteorite do not correspond to the temperatures attained. The metamorphic conditions are shown to be a function of the primary composition of the accreted minerals and of two metamorphic phases, progressive and retrogressive. First, a prograde phase led to textural maturation and equilibration of the chemical composition of silicates and oxides. The peak metamorphic temperatures were at least ~700ºC for the type 3.8. and 4 material, and up to ~1000ºC in H6 clasts i.e., sufficient to locally give rise to partial melting. The following retrograde metamorphism led to compositional re-equilibration of minerals and textural re-equilibration of minerals with partial melts. The cooling rate during retrograde metamorphism down to at least ~700ºC was low, which allowed potassium feldspar to form patches in Na-plagioclase and pseudobrookite-armalcolite breakdown to form an association of ilmenite and rutile. The two-phase metamorphic evolution of the Pułtusk breccia was the most likely the result of impact heating, which affected the parent body in its very early history.
    • 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.
    • Thin walled pottery from Alife (Northern Campania, Italy)

      Grifa, C; De Bonis, A; Guarino, V; Petrone, CM; Germinario, C; Mercurio, M; Soricelli, G; Langella, A; Morra, V (2015-04)
    • Time for a rethink: time sub-sampling methods in disparity-through-time analyses

      Guillerme, T; Cooper, N; Smith, A (The Palaeontological Association, 2018-04-22)
      Disparity‐through‐time analyses can be used to determine how morphological diversity changes in response to mass extinctions, or to investigate the drivers of morphological change. These analyses are routinely applied to palaeobiological datasets, yet, although there is much discussion about how to best calculate disparity, there has been little consideration of how taxa should be sub‐sampled through time. Standard practice is to group taxa into discrete time bins, often based on stratigraphic periods. However, this can introduce biases when bins are of unequal size, and implicitly assumes a punctuated model of evolution. In addition, many time bins may have few or no taxa, meaning that disparity cannot be calculated for the bin and making it harder to complete downstream analyses. Here we describe a different method to complement the disparity‐through‐time tool‐kit: time‐slicing. This method uses a time‐calibrated phylogenetic tree to sample disparity‐through‐time at any fixed point in time rather than binning taxa. It uses all available data (tips, nodes and branches) to increase the power of the analyses, specifies the implied model of evolution (punctuated or gradual), and is implemented in R. We test the time‐slicing method on four example datasets and compare its performance in common disparity‐through‐time analyses. We find that the way we time sub‐sample taxa can change our interpretations of the results of disparity‐through‐time analyses. We advise using multiple methods for time sub‐sampling taxa, rather than just time binning, to gain a better understanding disparity‐through‐time.
    • Time-calibrated molecular phylogeny of pteropods

      Burridge, AK; Hornlein, C; Janssen, AW; Hughes, M; Bush, SL; Marletaz, F; Gasca, R; Pierrot-Bults, AC; Michel, E; Todd, JA; et al. (2017-06-12)
    • The timescale of early land plant evolution

      Morris, JL; Puttick, MN; Clark, JW; Edwards, D; Kenrick, P; Pressel, S; Wellman, CH; Yang, Z; Schneider, Harald; Donoghue, PCJ (National Academy of Sciences of the United States of America, 2018-03-06)
      Establishing the timescale of early land plant evolution is essential for testing hypotheses on the coevolution of land plants and Earth’s System. The sparseness of early land plant megafossils and stratigraphic controls on their distribution make the fossil record an unreliable guide, leaving only the molecular clock. However, the application of molecular clock methodology is challenged by the current impasse in attempts to resolve the evolutionary relationships among the living bryophytes and tracheophytes. Here, we establish a timescale for early land plant evolution that integrates over topological uncertainty by exploring the impact of competing hypotheses on bryophyte−tracheophyte relationships, among other variables, on divergence time estimation. We codify 37 fossil calibrations for Viridiplantae following best practice. We apply these calibrations in a Bayesian relaxed molecular clock analysis of a phylogenomic dataset encompassing the diversity of Embryophyta and their relatives within Viridiplantae. Topology and dataset sizes have little impact on age estimates, with greater differences among alternative clock models and calibration strategies. For all analyses, a Cambrian origin of Embryophyta is recovered with highest probability. The estimated ages for crown tracheophytes range from Late Ordovician to late Silurian. This timescale implies an early establishment of terrestrial ecosystems by land plants that is in close accord with recent estimates for the origin of terrestrial animal lineages. Biogeochemical models that are constrained by the fossil record of early land plants, or attempt to explain their impact, must consider the implications of a much earlier, middle Cambrian–Early Ordovician, origin.
    • To remain or leave: Dispersal variation and its genetic consequences in benthic freshwater invertebrates

      Ruggeri, Paolo; Pasternak, E; Okamura, B (Wiley, 2019-10-18)
      Variation in dispersal capacity may influence population genetic variation and relatedness of freshwater animals thus demonstrating how life‐history traits influence patterns and processes that in turn influence biodiversity. The majority of studies have focused on the consequences of dispersal variation in taxa inhabiting riverine systems whose dendritic nature and upstream/downstream gradients facilitate characterizing populations along networks. We undertook extensive, large‐scale investigations of the impacts of hydrological connectivity on population genetic variation in two freshwater bryozoan species whose dispersive propagules (statoblasts) are either attached to surfaces (Fredericella sultana) or are released as buoyant stages (Cristatella mucedo) and that live primarily in either lotic (F. sultana) or lentic environments (C. mucedo). Describing population genetic structure in multiple sites characterized by varying degrees of hydrological connectivity within each of three (or four) UK regions enabled us to test the following hypotheses: (1) genetic diversity and gene flow will be more influenced by hydrological connectivity in populations of C. mucedo (because F. sultana dispersal stages are retained); (2) populations of F. sultana will be characterized by greater genetic divergence than those of C. mucedo (reflecting their relative dispersal capacities); and (3) genetic variation will be greatest in F. sultana (reflecting a propensity for genetic divergence as a result of its low dispersal potential). We found that hydrological connectivity enhanced genetic diversity and gene flow among C. mucedo populations but not in F. sultana while higher overall measures of clonal diversity and greater genetic divergence characterized populations of F. sultana. We suggest that genetic divergence over time within F. sultana populations reflects a general constraint of releasing propagules that might eventually be swept to sea when taxa inhabit running waters. In contrast, taxa that primarily inhabit lakes and ponds may colonize across hydrologically connected regions, establishing genetically related populations. Our study contributes more nuanced views about drivers of population genetic structures in passively dispersing freshwater invertebrates as outlined by the Monopolization Hypothesis (Acta Oecologica, 23, 2002, 121) by highlighting how a range of demographic and evolutionary processes reflect life‐history attributes of benthic colonial invertebrates (bryozoans) and cyclically parthenogenetic zooplankton. In addition, growing evidence that genetic divergence may commonly characterize populations of diverse groups of riverine taxa suggests that organisms inhabiting lotic systems may be particularly challenged by environmental change. Such change may predispose riverine populations to extinction as a result of genetic divergence combined with limited dispersal and gene flow.