Search results for " species"
showing 10 items of 2593 documents
Cytosolic calcium rises and related events in ergosterol-treated Nicotiana cells
2011
International audience; The typical fungal membrane component ergosterol was previously shown to trigger defence responses and protect plants against pathogens. Most of the elicitors mobilize the second messenger calcium, to trigger plant defences. We checked the involvement of calcium in response to ergosterol using Nicotiana plumbaginifolia and Nicotiana tabacum cv Xanthi cells expressing apoaequorin in the cytosol. First, it was verified if ergosterol was efficient in these cells inducing modifications of proton fluxes and increased expression of defence-related genes. Then, it was shown that ergosterol induced a rapid and transient biphasic increase of free [Ca2þ]cyt which intensity dep…
Marine reserves: size and age do matter
2008
Marine reserves are widely used throughout the world to prevent overfishing and conserve biodiversity, but uncertainties remain about their optimal design. The effects of marine reserves are heterogeneous. Despite theoretical findings, empirical studies have previously found no effect of size on the effectiveness of marine reserves in protecting commercial fish stocks. Using 58 datasets from 19 European marine reserves, we show that reserve size and age do matter: Increasing the size of the no-take zone increases the density of commercial fishes within the reserve compared with outside; whereas the size of the buffer zone has the opposite effect. Moreover, positive effects of marine reserve…
Structure of insect community in the fungus Inonotus radiatus in riparian boreal forests
2016
ABSTRACTBasidiomes of polypore fungi host many insects. Yet systematic information about insect assemblages from most fungal species is lacking. We studied the insect community associated with the wood-decaying fungus Inonotus radiatus (Sowerby: Fr.) P. Karst. (Hymenochaetales). More specifically, we studied the effect of successional stage and weight of basidiomes, as well as shore exposition (north or south), on species richness and composition, as well as occurrence and abundance of the most abundant fungivores. Basidiomes were collected from riparian forests at five lakes in Sweden. Insects were reared out from the basidiomes in the laboratory. A total of 5645 adult insect individuals o…
Hydrology Affects Environmental and Spatial Structuring of Microalgal Metacommunities in Tropical Pacific Coast Wetlands
2016
The alternating climate between wet and dry periods has important effects on the hydrology and therefore on niche-based processes of water bodies in tropical areas. Additionally, assemblages of microorganism can show spatial patterns, in the form of a distance decay relationship due to their size or life form. We aimed to test spatial and environmental effects, modulated by a seasonal flooding climatic pattern, on the distribution of microalgae in 30 wetlands of a tropical dry forest region: the Pacific coast of Costa Rica and Nicaragua. Three surveys were conducted corresponding to the beginning, the highest peak, and the end of the hydrological year during the wet season, and species abun…
Immigrant Tortricidae: Holarctic versus Introduced Species in North America
2020
In support of a comprehensive update to the checklist of the moths of North America, we attempt to determine the status of 151 species of Tortricidae present in North America that may be Holarctic, introduced, or sibling species of their European counterparts. Discovering the natural distributions of these taxa is often difficult, if not impossible, but several criteria can be applied to determine if a species that is present in both Europe and North America is natively Holarctic, introduced, or represented by different but closely related species on each continent. We use DNA barcodes (when available), morphology, host plants, and historical records (literature and museum specimens) to mak…
The structure of ant assemblages in an urban area of Helsinki, southern Finland
2008
We collected ants in ten replicated habitat types of an urban island and described their assemblages using Non-metric Multidimensional Scaling and Multivariate Regression Trees. Lasius niger was the most abundant species, followed by Myrmica rubra, Formica fusca, L. flavus and L. platythorax; these species comprised 87% of all 1133 nests of the 16 species found. Ant assemblages changed gradually from open habitats to sites with closed tree canopy. Species most tolerant to urban pressure were L. niger, L. flavus and M. rugulosa, whereas forest-associated species were scarce or absent. Successful urban species had extensive (Palaearctic) or more limited (Euro-Siberian) distribution. Common an…
A modified niche model for generating food webs with stage‐structured consumers: The stabilizing effects of life‐history stages on complex food webs
2021
Abstract Almost all organisms grow in size during their lifetime and switch diets, trophic positions, and interacting partners as they grow. Such ontogenetic development introduces life‐history stages and flows of biomass between the stages through growth and reproduction. However, current research on complex food webs rarely considers life‐history stages. The few previously proposed methods do not take full advantage of the existing food web structural models that can produce realistic food web topologies.We extended the niche model developed by Williams and Martinez (Nature, 2000, 404, 180–183) to generate food webs that included trophic species with a life‐history stage structure. Our me…
The conservation status of the world's freshwater molluscs
2021
With the biodiversity crisis continuing unchecked, we need to establish levels and drivers of extinction risk, and reassessments over time, to effectively allocate conservation resources and track progress towards global conservation targets. Given that threat appears particularly high in freshwaters, we assessed the extinction risk of 1428 randomly selected freshwater molluscs using the IUCN Red List Categories and Criteria, as part of the Sampled Red List Index project. We show that close to one-third of species in our sample are estimated to be threatened with extinction, with highest levels of threat in the Nearctic, Palearctic and Australasia and among gastropods. Threat levels were hi…
Scale- and taxon-dependent patterns of plant diversity in steppes of Khakassia, South Siberia (Russia)
2016
The drivers of plant richness at fine spatial scales in steppe ecosystems are still not sufficiently understood. Our main research questions were: (i) How rich in plant species are the natural steppes of Southern Siberia compared to natural and semi-natural grasslands in other regions of the Palaearctic? (ii) What are the main environmental drivers of the diversity patterns in these steppes? (iii) What are the diversity-environment relationships and do they vary between spatial scales and among different taxonomic groups? We sampled the steppe vegetation (vascular plants, bryophytes and lichens) in Khakassia (Russia) with 39 nested-plot series (0.0001-100-m(2) plot size) and 54 additional 1…
Formalized classification of European fen vegetation at the alliance level
2017
AimsPhytosociological classification of fen vegetation (Scheuchzerio palustris-Caricetea fuscae class) differs among European countries. Here we propose a unified vegetation classification of European fens at the alliance level, provide unequivocal assignment rules for individual vegetation plots, identify diagnostic species of fen alliances, and map their distribution.LocationEurope, western Siberia and SE Greenland.Methods29 049 vegetation-plot records of fens were selected from databases using a list of specialist fen species. Formal definitions of alliances were created using the presence, absence and abundance of Cocktail-based species groups and indicator species. DCA visualized the s…