Search results for "ISH"
showing 10 items of 7752 documents
Can we rely on selected genetic markers for population identification? Evidence from coastal Atlantic cod
2018
Abstract The use of genetic markers under putative selection in population studies carries the potential for erroneous identification of populations and misassignment of individuals to population of origin. Selected markers are nevertheless attractive, especially in marine organisms that are characterized by weak population structure at neutral loci. Highly fecund species may tolerate the cost of strong selective mortality during early life stages, potentially leading to a shift in offspring genotypes away from the parental proportions. In Atlantic cod, recent genetic studies have uncovered different genotype clusters apparently representing phenotypically cryptic populations that coexist i…
Potential of a no‐take marine reserve to protect home ranges of anadromous brown trout (Salmo trutta)
2018
The extent to which no-take marine reserves can benefit anadromous species requires examination. Here, we used acoustic telemetry to investigate the spatial behavior of anadromous brown trout (sea trout, Salmo trutta) in relation to a small marine reserve (similar to 1.5 km(2)) located inside a fjord on the Norwegian Skagerrak coast. On average, sea trout spent 42.3 % (+/- 5.0% SE) of their time in the fjord within the reserve, a proportion similar to the area of the reserve relative to that of the fjord. On average, sea trout tagged inside the reserve received the most protection, although the level of protection decreased marginally with increasing home range size. Furthermore, individual…
Infectivity of trematode eye flukes in farmed salmonid fish — Effects of parasite and host origins
2009
Abstract Parasites cause significant economic losses in fish farming, and knowledge of the mechanisms underlying their effects on hosts is an essential prerequisite of preventative procedures for the parasite problem in hatcheries. One such mechanism is local adaptation of parasites, which should lead to higher infectivity of parasites in sympatric host–parasite combinations compared to corresponding allopatric combinations. In this study, we investigated the infectivity of two ubiquitous species of trematode eye flukes, Diplostomum sp. and Tylodelphus clavata, in their farmed salmonid fish hosts with respect to origin of the parasite and the host. First, we exposed two anadromous and one l…
Morphological and molecular variability within the fig cultivar 'Dottato' in the Italian protected designation origin area "fichi di Cosenza"
2017
The morphological and molecular diversity among fig accessions of 'Dottato', found in the PDO "Fichi di Cosenza" area was studied by evaluating 24 morphological traits and by genotyping with 18 microsatellite markers. The microsatellite allelic profiles among the putative clones of 'Dottato' indicated a moderate genetic variability, discriminating unambiguously most of the accessions. Only two groups of identity were found. The average expected and observed heterozygosity were 0.43 and 0.62, respectively. The mean polymorphic information content (PIC) was 0.4, varying from 0.08 (LMFC26) to 0.067 (FCUP 38-6). The morphological clustering allowed the distinction of all genotypes. Some genotyp…
Migratory passage structures at hydropower plants as potential physiological and behavioural selective agents
2019
Anthropogenic activities affect fish populations worldwide. River dams have profound impacts on ecosystems by changing habitats and hindering migration. In an effort to counteract such effects, a range of mitigation measures have been installed at hydroelectric power plants. However, not all individuals in a population use these measures, potentially creating strong selection processes at hydroelectric power plants. This may be especially true during migration; fish can get heavily delayed or pass through a hydropower turbine, thus facing increased mortality compared with those using a safe bypass route. In this study, we quantify migration route choices of descending wild passive integrate…
Long-term effects of no tillage treatment on soil N availability, N uptake, and 15N-fertilizer recovery of durum wheat differ in relation to crop seq…
2016
Abstract No tillage (NT) soil management has largely been promoted because of its potential to generate both economic and environmental benefits. However, it often leads to reductions in crop yield and quality, which in many cases have been attributed to the effects this technique has on the nitrogen (N) dynamics in the soil–plant system. This 2-year study, performed within a long-term experiment in which NT was continuously applied for over 15 years, aimed to verify whether and to what extent the use of NT affects soil N availability, recovery of 15 N-labeled fertilizer, and N use efficiency (NUE) and its components (N uptake efficiency, NUpE; N utilization efficiency, NUtE). Durum wheat w…
Effects of species and soil-nitrogen availability on root system architecture traits - study on a set of weed and crop species
2017
Better managing crop : weed competition in cropping systems while reducing both nitrogen and herbicide inputs is a real challenge that requires a better understanding of crop and weed root architecture in relation to soil-nitrogen availability. An original approach was used which considered the parameters of a simulation model of root architecture as traits to analyse (a) the interspecific diversity of root system architecture, and (b) its response to soil-nitrogen availability. Two greenhouse experiments were conducted using three crop and nine weed species grown at two contrasted concentrations of soil-nitrogen availability. Plant traits were measured to characterise both overall plant gr…
Blackgrass (Alopecurus myosuroides Huds.) seed dispersal from a single plant and its consequences on weed infestation
2001
Blackgrass (Alopecurus myosuroides Huds.) seed dispersal from single mother-plants was studied in two experiments. For the first experiment, eight blackgrass plants of different heights and number of ears were produced in a greenhouse with the help of different in sowing densities and nitrogen nutrition levels. At the beginning of seed shedding, the plants were placed outside, and seeds were gathered daily. Daily seed dispersal was analysed by fitting a Weibull equation to the number of seeds as a function of distance to the mother-plant. The second experiment was carried out in a field comprising winter barley and spring barley plots as well as bare soil. In each of these three parts, two …
History of land-use intensity can modify the relationship between functional complexity of the soil fauna and soil ecosystem services - A microcosm s…
2012
Abstract Agricultural intensification generally results in the loss of soil organic matter, a decline in soil biodiversity, and the reduced ability of soils to retain nutrients. Intensified land-use can bring about legacy effects in soil ecosystem services that may last for hundreds of years after the cessation of agricultural practises. We studied, in a laboratory pot experiment, whether legacy effects due to intensive land/soil management (intensively managed wheat field) can be alleviated by restoring the disturbed soil with soil fauna typical of less managed soils (grassland soil). We also compared the effects of functional complexity of the soil fauna (microfauna, microfauna + mesofaun…
Variable impacts of enchytraeid worms and ectomycorrhizal fungi on plant growth in raw humus soil treated with wood ash
2007
Abstract An increasing amount of evidence shows the context dependent nature of various biotic interactions across terrestrial and aquatic ecosystems. We established a laboratory experiment to study whether the effects of Cognettia sphagnetorum (Enchytraeidae) and ectomycorrhizal fungi on Scots pine (Pinus sylvestris) seedling growth are influenced by wood ash application. Acidic coniferous forest soil was treated with wood ash at 5000 kg ha−1 or left as ash-free control and inoculated with soil saprotrophic microbes and nematodes. The microcosms were destructively sampled 26 and 51 weeks after initiation of the experiment. We measured enchytraeid and pine seedling biomass, abundance of nem…