Search results for "Eastern"
showing 10 items of 324 documents
Pseudoshasticrioceras bersaci nov. sp. (Ammonoidea, Gassendiceratinae), and new ammonite biohorizon for the Upper Barremian of southeastern France
2009
International audience; Research in the Feraudianus Subzone of the Sartousiana Zone of the Barremian stage led to the discovery of a new species of Pseudoshasticrioceras: P. bersaci nov. sp. Its study provides evidence concerning the developments of the latest Gassendiceratinae BERT et alii, 2006, and the relationship between the genus Pseudoshasticrioceras DELANOY, 1998, and Gassendiceras BERT et alii, 2006. In particular, this new species is derived from Pseudoshasticrioceras magnini (DELANOY, 1992) by a minor revision in the processes of ontogenesis (retardation of ornamentation - neoteny). However, the evolution towards Pseudoshasticrioceras autrani DELANOY, 1998, implies a "failure" in…
Plasticity of response of tree-ring width of Scots pine provenances to weather extremes in Latvia
2019
Abstract Climatic changes and weather extremes are causing shifts in distribution of tree species, affecting productivity of forests. With the northwards advance of deciduous species in Northern Europe, Scots pine (Pinus sylvestris L.) is predicted to decrease survival and productivity. Nevertheless, Scots pine have adapted to diverse environments, hence selection among its populations could be applied to sustain productivity of stands under changing climate. In this study, sensitivity of tree-ring width of Eastern European provenances of Scots pine differing by field performance (Dippoldiswalde, Eibenstock, Rytel, Gustrow, and Kalsnava) to weather extremes in three trials in Latvia (hemibo…
Frequent colonization and little in situ speciation in Senecio in the tropical alpine-like islands of eastern Africa.
2016
Premise of the study Floras of continental habitat islands, like those of islands, originate mostly through colonization, which can be followed by in situ speciation. We here address the question of the relative importance of colonization and in situ diversification in the high-altitude areas of the eastern African high mountains, the tropical Afroalpine Region, using the most species-rich genus in the region, Senecio, as an example. Methods We expanded earlier Senecioneae phylogenies by adding more tropical African species and analyzed our phylogenetic tree biogeographically. Key results Senecio contains at least five clades with tropical African species, all of them containing tropical af…
Novel mutations in the voltage-gated sodium channel of pyrethroid-resistant Varroa destructor populations from the Southeastern USA
2016
The parasitic mite Varroa destructor has a significant worldwide impact on bee colony health. In the absence of control measures, parasitized colonies invariably collapse within 3 years. The synthetic pyrethroids tau-fluvalinate and flumethrin have proven very effective at managing this mite within apiaries, but intensive control programs based mainly on one active ingredient have led to many reports of pyrethroid resistance. In Europe, a modification of leucine to valine at position 925 (L925V) of the V. destructor voltage-gated sodium channel was correlated with resistance, the mutation being found at high frequency exclusively in hives with a recent history of pyrethroid treatment. Here,…
Do mosses really exhibit so large distribution ranges? Insights from the integrative taxonomic study of the Lewinskya affinis complex (Orthotrichacea…
2019
The strikingly lower number of bryophyte species, and in particular of endemic species, and their larger distribution ranges in comparison with angiosperms, have traditionally been interpreted in terms of their low diversification rates associated with a high long-distance dispersal capacity. This hypothesis is tested here with Lewinskya affinis (≡ Orthotrichum affine), a moss species widely spread across Europe, North and East Africa, southwestern Asia, and western North America. We tested competing taxonomic hypotheses derived from separate and combined analyses of multilocus sequence data, morphological characters, and geographical distributions. The best hypothesis, selected by a Bayes …
A Migratory Divide Among Red-Necked Phalaropes in the Western Palearctic Reveals Contrasting Migration and Wintering Movement Strategies
2019
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Temperature controls organic carbon sequestration in a subarctic lake
2016
AbstractWidespread ecological reorganizations and increases in organic carbon (OC) in lakes across the Northern Hemisphere have raised concerns about the impact of the ongoing climate warming on aquatic ecosystems and carbon cycling. We employed diverse biogeochemical techniques on a high-resolution sediment record from a subarctic lake in northern Finland (70°N) to examine the direction, magnitude and mechanism of change in aquatic carbon pools prior to and under the anthropogenic warming. Coupled variation in the elemental and isotopic composition of the sediment and a proxy-based summer air temperature reconstruction tracked changes in aquatic production, depicting a decline during a coo…
Shell repair process in the green ormer Haliotis tuberculata: a histological and microstructural study.
2008
In the present paper, juvenile and adult shells of the green ormer Haliotis tuberculata ('Oreille de Saint-Pierre') were perforated in a zone close to the shell edge and the shell repair process was followed at two levels: (1) by observing the histology of the calcifying mantle in the repair zone and (2) by analyzing with SEM the microstructure of the shell repair zone. Histological data clearly show the presence of calcium carbonate granules into the connective tissues, but not in the epithelial cells. This suggests that calcium carbonate granules are synthesized by sub-epithelial cells and actively transported through the epithelium to the repair zone, via a process which may be similar t…
Succession in ant communities (Hymenoptera: Formicidae) in deciduous forest clear-cuts - an Eastern European case study
2017
Clear-cutting, the main method of harvesting in many forests in the world, causes a series of dramatic environmental changes to the forest habitat and removes habitat resources for arboreal and epigeal species. It results in considerable changes in the composition of both plant and animal communities. Ants have many critical roles in the maintenance and functioning of forest ecosystems. Therefore, the response of ants to clear-cutting and the time it takes for an ant community to recover after clear-cutting are important indicators of the effect of this harvesting technique on the forest ecosystem. We investigated ground-dwelling ant communities during secondary succession of deciduous fore…
Revision of the west african species of scyllarus fabricius, 1775 (Decapoda: Achelata: Scyllaridae), with the description of three phyllosoma stages …
2020
West African species of Scyllarus Fabricius, 1775 (Achelata, Scyllaridae) are poorly known, mostly due to the difficulties of sampling Eastern Atlantic tropical waters. Recent expeditions carried out by the Universidad de Cádiz and the Instituto Español de Oceanografía collected phyllosoma larvae from Cape Verde Islands (CVI) and fresh Scyllarus adults from continental West Africa. Larval stages VII, IX, and X (final stage) of S. caparti Holthuis, 1952 are analyzed using DNA barcoding methods and described for the first time. A comprehensive identification key is provided, summarizing our current knowledge on the phyllosomas of Scyllarus. Together with a revision of museum collections, the …