Search results for "Arctic"
showing 10 items of 565 documents
Arctica islandica (Bivalvia): A unique paleoenvironmental archive of the northern North Atlantic Ocean
2013
Abstract High-resolution environmental proxy data from the extratropical North Atlantic prior to the instrumental era are of critical importance to decipher processes and mechanisms of global change. In this regard, shells of the extremely long-lived bivalve mollusc, Arctica islandica ( Linnaeus, 1767 ), have gained particular attention during the last decade because they serve as reliable, subseasonally resolved multi-proxy archives of environmental variability in that very region. With a lifespan of more than 500 years, A. islandica is the longest-lived solitary animal. Its shell grows periodically throughout life and contains distinct annual and daily growth increments. These growth patt…
GrassPlot v. 2.00 : first update on the database of multi-scale plant diversity in Palaearctic grasslands
2019
Abstract: GrassPlot is a collaborative vegetation-plot database organised by the Eurasian Dry Grassland Group (EDGG) and listed in the Global Index of Vegetation-Plot Databases (GIVD ID EU-00-003). Following a previous Long Database Report (Dengler et al. 2018, Phyto- coenologia 48, 331–347), we provide here the first update on content and functionality of GrassPlot. The current version (GrassPlot v. 2.00) contains a total of 190,673 plots of different grain sizes across 28,171 independent plots, with 4,654 nested-plot series including at least four grain sizes. The database has improved its content as well as its functionality, including addition and harmonization of header data (land use,…
Climate change and cyclic predator-prey population dynamics in the high Arctic.
2009
The high Arctic has the world's simplest terrestrial vertebrate predator–prey community, with the collared lemming being the single main prey of four predators, the snowy owl, the Arctic fox, the long-tailed skua, and the stoat. Using a 20-year-long time series of population densities for the five species and a dynamic model that has been previously parameterized for northeast Greenland, we analyzed the population and community level consequences of the ongoing and predicted climate change. Species' responses to climate change are complex, because in addition to the direct effects of climate change, which vary depending on species' life histories, species are also affected indirectly due to…
Dicrocoelium dendriticum found in a Bronze Age cemetery in western Iran in the pre-Persepolis period: The oldest Asian palaeofinding in the present h…
2015
Dicrocoeliasis of animals and humans is caused by trematode species of the genus Dicrocoelium, mainly Dicrocoelium dendriticum in ruminants of the Holarctic region. D. dendriticum may be considered an old parasite, probably related to the appearance and diversification of Eurasian ovicaprines, occurred 14.7-14.5 million years ago. The oldest palaeoparasitological findings of Dicrocoelium in domestic animals and humans date from more than 5000 years BC in Europe. Eggs of D. dendriticum have been found in a burial of a Bronze Age cemetery (2600-2200 BC) close to Yasuj city, southwestern Iran. This is the oldest finding of D. dendriticum in the Near East, where present human infection reports …
Data from: Exposing the structure of an Arctic food web
2016
How food webs are structured has major implications for their stability and dynamics. While poorly studied to date, arctic food webs are commonly assumed to be simple in structure, with few links per species. If this is the case, then different parts of the web may be weakly connected to each other, with populations and species united by only a low number of links. We provide the first highly resolved description of trophic link structure for a large part of a high-arctic food web. For this purpose, we apply a combination of recent techniques to describing the links between three predator guilds (insectivorous birds, spiders, and lepidopteran parasitoids) and their two dominant prey orders …
Investigation of European shot-hole borer, Xyleborus dispar (Coleoptera, Scolytidae), in apple orchards of Latvia
2015
European shot-hole borer is known to occur on a wide range of deciduous trees and frequently found on fruit trees in most of the Holarctic. During the last years increased activity of this beetle<em> </em>contributed necessity for investigation of it in apple orchards of Latvia. Because of the latent behavior it is difficult to control distribution of <em>Xyleborus dispar</em>. Often insecticides are not effective, especially if not used in an appropriate time and methods of integrated or biological plant protection are needed. In the current study, results of two year monitoring of <em>X. dispar</em> flying activity and effectiveness of two types of stic…
Cryptic Diversity in Mongolian Vespertilionid Bats (Vespertilionidae, Chiroptera, Mammalia). Results of the Mongolian-German Biological Expeditions S…
2012
In contrast to the Eastern Palaearctic region a high degree of cryptic diversity was discovered among temperate bats of the Western Palaearctic region in the last ten years. Climatic oscillations caused severe changes in the distribution of species throughout the Palaearctic region during the Pleistocene. Exploring multiple taxa can help to understand general evolutionary differentiation processes. In the present study genetic variation within and among 94 Mongolian vespertilionid bats of six genera (Hypsugo, Eptesicus, Vespertilio, Myotis, Plecotus, and Nyctalus) was screened by sequencing a 798 bp fragment of the mitochondrial ND1 gene and then subsequently compared with those of Western …
Mise en évidence d’une dynamique de fleuves de glace durant la glaciation ordovicienne par l’enregistrement géomorphologique
2007
On Contemporary Ice streams the most important factor controlling polar ice-sheet sheet stability and ice flowing occurs in ice streams. On Pleistocene Ice Sheet, Ice stream can be located using several geomorphologic criteria predict from known characteristic of contemporary ice streams, these criteria defining the conceptual Ice Stream land system model. But nowadays, during fossil glaciations, ice streams characterization is still poorly documented and only few studies illustrate fast ice velocity. In this work, we characterize geomorphological markers of ice stream activity in order to define the Ordovician ice stream glacial landsystem. The study area is located in Sahara from Niger to…
On the Age of Leprosy
2014
Leprosy is a chronic infection of the skin and nerves caused by Mycobacterium leprae and the newly discovered Mycobacterium lepromatosis. Human leprosy has been documented for millennia in ancient cultures. Recent genomic studies of worldwide M. leprae strains have further traced it along global human dispersals during the past ∼ 100,000 years. Because leprosy bacilli are strictly intracellular, we wonder how long humans have been affected by this disease-causing parasite. Based on recently published data on M. leprae genomes, M. lepromatosis discovery, leprosy bacilli evolution, and human evolution, it is most likely that the leprosy bacilli started parasitic evolution in humans or early h…
Phylogeography and genetic variation of Triatoma dimidiata, the main Chagas disease vector in Central America, and its position within the genus Tria…
2008
Background Among Chagas disease triatomine vectors, the largest genus, Triatoma, includes species of high public health interest. Triatoma dimidiata, the main vector throughout Central America and up to Ecuador, presents extensive phenotypic, genotypic, and behavioral diversity in sylvatic, peridomestic and domestic habitats, and non-domiciliated populations acting as reinfestation sources. DNA sequence analyses, phylogenetic reconstruction methods, and genetic variation approaches are combined to investigate the haplotype profiling, genetic polymorphism, phylogeography, and evolutionary trends of T. dimidiata and its closest relatives within Triatoma. This is the largest interpopulational …