Search results for "RCT"
showing 10 items of 1934 documents
Where are you from, stranger? The enigmatic biogeography of North African pond turtles (Emys orbicularis)
2014
Abstract The European pond turtle (Emys orbicularis) is a Nearctic element in the African fauna and thought to have invaded North Africa from the Iberian Peninsula. All North African populations are currently identified with the subspecies E. o. occidentalis. However, a nearly range-wide sampling in North Africa used for analyses of mitochondrial and microsatellite DNA provides evidence that only Moroccan populations belong to this taxon, while eastern Algerian and Tunisian pond turtles represent an undescribed distinct subspecies. These two taxa are most closely related to E. o. galloitalica with a native distribution along the Mediterranean coast of northern Spain through southern France …
Revision of the genusXyalaspisHartig, 1843 (Hymenoptera: Figitidae: Anacharitinae) in the Western Palaearctic
2015
ABSTRACT A revision of Xyalaspis Hartig, 1843 (Hymenoptera: Anacharitinae) in the Western Palaearctic region is given. Xyalaspis spinigera Reinhard, 1860 and Xyalaspis subulifera (Thomson, 1862) are synonymized with Xyalaspis laevigata Hartig, 1843 and Xyalaspis rugosa Hartig, 1843 respectively, and their distribution areas are extended. A new species Xyalaspis pseudolaevigata n. sp. is described from France. One species previously assigned to the genus Xyalaspis, X. laevis (Hedicke, 1914), is transferred to Aegilips Haliday, 1835. Diagnostic characters are illustrated and data about biology, distribution and morphological variability of the studied species are presented and discussed. A ke…
<strong>Revision of the Western Palaearctic species of the genus <em>Dinotrema</em> Foerster, 1862 (Hymenoptera, Braconidae, Alysii…
2014
The first comprehensive revision of the Western Palaearctic species of the genus Dinotrema Foerster, 1862 is provided. 174 species of this genus are redescribed and illustrated. Ten species are described as new, viz, D. acompressum sp. nov., D. cahitum sp. nov., D. collybiae sp. nov., D. digitatum sp. nov., D. glabrideum sp. nov., D. helote sp. nov., D. lepiotae sp. nov., D. norwegicum sp. nov., D. oxybellum sp. nov. and D. torpi sp. nov. The following new combinations are suggested: Dinotrema adventum (Fischer), comb. nov., D. aurelianum (Fischer), comb. nov., D. cetiusmonte (Fischer), comb. nov., D. converginerve (Fischer), comb. nov., D. intermissum (Fischer), comb. nov., D. leptocorne (…
Effect of organic matrices on the determination of the trace element chemistry (Mg, Sr, Mg/Ca, Sr/Ca) of aragonitic bivalve shells (<i>Arctica …
2010
The element chemistry of biogenic carbonates can provide important data on past environments. However, the Sr/Ca and Mg/Ca ratios as well as the Mg and Sr concentrations of biological carbonates, especially aragonitic bivalves often depart from apparent thermodynamic equilibrium. When measured in situ by means of LA-ICP-MS, the Mg concentration is often substantially enriched (two- to threefold) near the organic-rich, annual growth lines. To test the hypothesis that some organic components exert a major influence on the skeletal metal content, the element chemistry of different shell components (insoluble organic matrix, IOM; dissolved CaCO3 and soluble organics, SOM) of Arctica islandica w…
Coralline algal growth-increment widths archive North Atlantic climate variability
2011
Over the past decade coralline algae have increasingly been used as archives of paleoclimate information. Encrusting coralline algae, which deposit annual growth increments in a high Mg-calcite skeleton, are amongst the longest-lived shallow marine organisms. In fact, a live-collected plant has recently been shown to have lived for at least 850 years based on radiometric dating. While a number of investigations have successfully used geochemical information of coralline algal skeletons to reconstruct sea surface temperatures, less attention has been paid to employ growth increment widths as a temperature proxy. Here we explore the relationship between growth and environmental parameters in …
Accurate increment identification and the spatial extent of the common signal in fiveArctica islandicachronologies from the Fladen Ground, northern N…
2009
[1] The creation of networks of shell-based chronologies which can provide regionally extensive high-resolution proxies for the marine environment depends on the spatial extent of the common environmental signal preserved in the shell banding and on the reliability of the dating model. Here Arctica islandica chronologies from five neighboring sites in the North Sea are compared, and the strength of the common environmental signal across distances up to 80 km is analyzed using statistical techniques derived from dendrochronology. The signal is found to be coherent across these distances. In a linked study, chronologies based on one of the same sites but constructed by two different research …
<p><strong><em>Diversispora valentina</em></strong><strong> (Diversisporaceae), a new species of arbuscular mycor…
2020
A new arbuscular mycorrhizal fungal species, Diversispora valentina, is described and illustrated. In the field, this species is associated with marine dunes located along the Mediterranean coast in eastern Spain. Spores of D. valentina occurred in sporocarps, in clusters, and singly in the soil or inside the roots of Ammophila arenaria (Poaceae), Elymus farctus (Poaceae), Otanthus maritimus (Asteraceae), and Echinophora spinosa (Apiaceae) in the six locations studied. A single-species culture of D. valentina was obtained using Trifolium repens as a host plant. The small subunit internal transcribed spacer and large subunit (SSU-ITS1-5.8S-ITS2-LSU) nrDNA sequences place the new species in t…
Die Ölblumensymbiosen - Parallelismus and andere Aspekte ihrer Entwicklung in Raum and Zeit1, 2
2009
The oil-bee/oil-flower relationships: parallelism and other aspects of their evolution in space and time A survey is given of our present knowledge and existing hypotheses concerning the biogeography, history, and phylogeny of plant taxa yielding fatty oil as a floral reward, and of the bee genera involved in their pollination. Four syngenetic complexes of the symbiosis arose convergently: The neotropical, the paleotropical, the holarctic, and the capensic complex. On the basis of the mutual structural adaptations of bees and flowers it is concluded that, in addition, parallelism within related groups as a result of a common tendency to develop the respective organs, has played an important…
THE ROLE OF THROMBIN IN CENTRAL NERVOUS SYSTEM ACTIVITY AND STROKE
2018
Background. Thrombin is a key factor of hemostasis, mediating the conversion of fibrinogen into fibrin. Along with prothrombin, of which thrombin is the active derivative, it has been found locally expressed in the central nervous system. This article aims to describe the role of thrombin in the normal functioning of the central nervous system and stroke.Methods. In this mini-review, the specialized databases Medscape, PubMed, and Web of Science, from the years 2003-2018, were used to find relevant documents by using MeSH terms: ”thrombin” and ”stroke”.Results. Prothrombin and thrombin influence neural development, protection and regeneration, thrombin being a relatively strong regulating f…
Fine-grain beta diversity in Palaearctic open vegetation: variability within and between biomes and vegetation types
2021
Aims: To quantify how fine-grain (within-plot) beta diversity differs among biomes and vegetation types. Study area: Palaearctic biogeographic realm. Methods: We extracted 4,654 nested-plot series with at least four different grain sizes between 0.0001 m² and 1,024 m² from the GrassPlot database spanning broad geographic and ecological gradients. Next, we calculated the slope parameter (z-value) of the power-law species–area relationship (SAR) to use as a measure of multiplicative beta diversity. We did this separately for vascular plants, bryophytes and lichens and for the three groups combined (complete vegetation). We then tested whether z-values differed between biomes, ecological-physi…