Testing decreasing variabililty of cockroach forewings through time using four Recent species: Blattella germanica, Polyphaga aegyptiaca, Shelfordella lateralis and Blaberus craniifer, with implications for the study of fossil cockroach forewings
Ross A.J.,National Museums Scotland
Insect Science | Year: 2012
Vršanský (2000) considered there is decreasing variability in the forewings of cockroaches through time, based on a study of fossil and Recent species. This study tests his theory, based on a study of four Recent species of cockroaches: Blattella germanica (Blattellidae), Polyphaga aegyptiaca (Polyphagidae), Shelfordella lateralis (Blattidae) and Blaberus craniifer (Blaberidae). The new results, based on the coefficient of variation (CV) of the number of veins, indicate that Recent species can be more variable than fossil species and therefore do not support the theory. The results also show that at least 30 complete wings of the same species are required for a reliable CV value that is comparable between species. © 2012 The Author Journal compilation © Institute of Zoology, Chinese Academy of Sciences.
Pinzari F.,Istituto Centrale per il Restauro e la Conservazione del Patrimonio Archivistico e Librario |
Tate J.,National Museums Scotland |
Bicchieri M.,Istituto Centrale per il Restauro e la Conservazione del Patrimonio Archivistico e Librario |
Rhee Y.J.,University of Dundee |
Gadd G.M.,University of Dundee
Environmental Microbiology | Year: 2013
Fungal biodeterioration of ivory was investigated with in vitro inoculation of samples obtained from boar and walrus tusks with the fungi Aspergillus niger and Serpula himantioides, species of known geoactive abilities. A combination of light and scanning electron microscopy together with associated analytical techniques was used to characterize fungal interactions with the ivory, including changes in ivory composition, dissolution and tunnelling, and the formation of new biominerals. The research was aimed at providing further understanding of the potential roles of fungi in the colonization and deterioration of ivory in terrestrial environments, but also contributes to our knowledge regarding the possible origins of the surface damage observed on early medieval sculptures made largely from walrus tusks, referred to as 'the Lewis hoard of gaming pieces', that were presumably produced for playing chess. The experiments have shown that the possibility of damage to ivory being caused by fungi is realistic. Scanning electron microscopy revealed penetration of fungal hyphae within cracks in the walrus tusk that showed also widespread tunnelling by fungal hyphae as well as 'fungal footprints' where the surface was etched as a consequence of mycelial colonization. Similar phenomena were observed with boar tusk ivory, while production of metabolites could lead to complete dissolution of the sample. Colonization of ivory and/or exposure to fungal activity lead to extensive secondary biomineral formation, and this was identified as calcium oxalate, mainly as the monohydrate, whewellite. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.
Candela Y.,National Museums Scotland
Earth-Science Reviews | Year: 2015
The distribution of brachiopod faunas around Laurentia during the Ordovician period was influenced by the dynamicity of the surrounding palaeo-continents. Laurentia seemed to have been somewhat static, straddling the palaeo-equator, whereas the late Ordovician was characterised by the later stages of the closure of the Iapetus Ocean, with Baltica, eastern Avalonia and a variety of exotic terranes docking the southern and south-eastern coasts of Laurentia. In the earliest Ordovician, 'primitive' taxa that originated in the Cambrian were major components of brachiopod faunas. Later in the early Ordovician some major, first appearances (plectambonitoids) contributed to increase the diversity of the faunas, and by the end of the middle Ordovician, a very diverse fauna had conquered the continent: strophomenoids first appeared, plectambonitoids increased importance, and overall rhynchonelliform diversity exploded. During the tectonically active Ordovician, orogenies created geographical barriers that accentuated the faunal differences between peri-Laurentian terranes and cratonic assemblages. The late Ordovician diversification of brachiopods is the result of several gradual events spanning the Dapingian to the Sandbian. From the Sandbian to the Katian, the Scoto-Appalachian fauna, which is characteristic of terranes in the vicinity of the south-eastern margin of Laurentia, retained its peculiarity and did not invade the epicontinental seas of Laurentia. By the Hirnantian, two main groups, characterised by well-defined climatically controlled provinces, can be differentiated. Although the Hirnantian was marked by drastic extinction events, part of Laurentia (notably the intracratonic platform) may be identified as a place of hospitality for brachiopod faunas as many taxa thrived across the extinction boundary, into the Silurian period. © 2014 Elsevier B.V.
Candela Y.,National Museums Scotland |
Harper D.A.T.,Palaeoecosystems Group
Earth and Environmental Science Transactions of the Royal Society of Edinburgh | Year: 2014
The generic assignments of some 200 Ordovician brachiopod species in the Barr and Lower Ardmillan (upper Darriwilian-lower Katian) succession, Girvan are reviewed and, where necessary, modified. This key database on the distribution and occurrence of a Laurentian-marginal brachiopod assemblage has featured in many analyses of global biogeography for the period and has confirmed the position of Girvan at relatively low latitudes. Revision of these taxonomic assignments within a modified stratigraphical framework permits closer comparisons with coeval faunas elsewhere around the palaeocontinent of Laurentia and beyond and allows the definition of a variety of brachiopod biofacies on a fault-controlled basin founded on a dismembered ophiolite. Copyright © The Royal Society of Edinburgh 2014.
Herman J.S.,National Museums Scotland |
Herman J.S.,University of York |
Searle J.B.,University of York |
Searle J.B.,Cornell University
Proceedings of the Royal Society B: Biological Sciences | Year: 2011
Genetic markers are often used to examine population history. There is considerable debate about the behaviour of molecular clock rates around the population-species transition. Nevertheless, appropriate calibration is critical to any inference regarding the absolute timing and scale of demographic changes. Here, we use a mitochondrial cyto chrome b gene genealogy, based entirely on modern sequences and calibrated from recent geophysical events, to date the post-glacial expansion of the Eurasian field vole (Micro tus agrestis), a widespread temperate mammal species. The phylogeo graphic structure reflects the subsequent expansion of populations that went through bottlenecks at the time of the Younger Dryas (ca 12 000 years BP) rather than the Last Glacial Maximum (LGM, ca 24 000 years BP), which is usually seen as the time when present-day patterns were determined. The nucleotide substitution rate that was estimated here, ca 4 _ 1027 substitutions/site/year, remains extremely high throughout the relevant time frame. Calibration with similarly high population-based substitution rates, rather than long-term rates derived from species divergence times, will show that post-LGM climatic events generated current phylogeo graphic structure in many other organisms from temperate latitudes. © 2011 The Royal Society.