Search results for "ABIOTIC"
showing 10 items of 201 documents
Life-history traits, abiotic environment and coexistence: The case of two cryptic rotifer species
2015
Abstract Trade-offs are important in life-history evolution and coexistence of competitors. However, how alternative life-history optima might promote competitor coexistence has received little attention. The rotifers Brachionus plicatilis and Brachionus manjavacas are two cryptic species with a considerable ecological overlap in relation to biotic factors. These species often co-occur in temporal brackish ponds characterised by environmental fluctuations. In these rotifers, sexual reproduction results in diapausing stages, which are able to survive through adverse conditions but constrain current population growth. In the present work, the differential responses of both cryptic rotifer spe…
Möglichkeiten und Grenzen einer Ökosystem-Rekonstruktion am Beispiel des spätpaläozoischen lakustrinen Paläo-Ökosystems. 1. Theoretische und methodis…
1998
In analogy to ecosystems, palaeoecosystems are defined here as the palaeocommunities of a given area and their relationships to the abiotic variables of their respective environments. They are characterized by (a) their species diversity, (b) the trophic structure of their palaeocommunities, based on their food webs, and (c), based on their detailed historical development, ecosystem functions such as stability, resilience, and succession. Due to numerous taphonomic biases, palaeocommunities can only be reconstructed from very few fossil horizons (taphocoenoses). Important conditions for such reconstructions are an uninterrupted vertical sequence of taphocoenoses with little time-averaging, …
Environmental drivers of breeding sites in blackfly species of medical and veterinary importance in eastern Spain
2021
Geographical distribution and abundance of the pupae of six blackfly species of medical and veterinary concern were studied in eastern Spain according to three different sets of explanatory variables including in-stream variables, both (i) abiotic (i.e., physicochemical) and (ii) biotic (i.e., richness and abundance of either taxonomically or ecologically close related taxa), as well as (iii) meteorological and landscape variables. The results showed specific habitat requirements for pupation in Simulium (Boophthora) erythrocephalum (De Geer, 1776) and Simulium (Wilhelmia) equinum (Linnaeus, 1758), two of the six species studied regarding elevation and temperature. While the rest of the spe…
Interrelationships between mycorrhizal symbiosis, soil pH and plant sex modify the performance of Antennaria dioica
2010
AM symbiosis is usually beneficial for plants, but the benefits gained may depend on the soil abiotic factors. In dioecious plants, female and male individuals have different resource demands and allocation patterns. As a consequence of these differences, it is logical to assume that female and male plants differ in their relationship with arbuscular mycorrhizal (AM) fungi, although this has rarely been examined. We used a factorial greenhouse experiment to investigate whether female and male plants in the dioecious model species Antennaria dioica have a different relationship with their AM symbionts under two soil pH levels. In particular, we asked: (1) Do the sexes in A. dioica have sex-s…
Annual cycles of apoptosis, DNA strand breaks, heat shock proteins, and metallothionen isoforms in dab (Limanda limanda): influences of natural facto…
2013
The present study was undertaken to investigate the influence of natural and anthropogenic stressors on the induction of apoptosis, metallothionein (MT) isoforms, heat shock proteins and DNA strand breaks in the marine flatfish dab (Limbanda limanda) Seasonal changes and possible physiological influences were evaluated over a 1-year period at a fixed location northwest of Helgoland in the German Bight. These results were compared with data from sampling sites in the North Sea and the Baltic Sea. Annual cycles could be observed for all parameters except for Cd. The data revealed that changes in biomarker are not only linked to physiological processes related to reproduction but also to facto…
Genetic variation in growth and development time under two selection regimes in Leptinotarsa decemlineata
2008
It is possible to predict the potential range of a species on the basis of its ecological characteristics and those of the invaded ecosystem. The existence of genetic variation indicates a species' potential to respond to new environmental conditions, thus facilitating its success as an invader. Accordingly, evolutionary and ecological approaches are needed to identify the factors explaining both species' range and their potential to invade new areas. We combined these two approaches and studied whether genetic variation in life-history traits under abiotic (temperature) and biotic (host plant) selection pressures contributes to the potential range expansion of Leptinotarsa decemlineata Say…
The soil as a reservoir for antagonists to plant diseases
2007
The soil is often considered the milieu providing support for plant roots, water and nutrients for plant growth. But it is also considered a hostile environment harbouring plant pathogenic nematodes, bacteria and fungi. The most common attitude is to try to eliminate the plant pathogenic organisms by biocidal treatments such as methyl bromide fumigation, which are dangerous for man and the environment. Beside this pathogen eradication strategy, another approach to control soil-borne plant diseases consists in studying the plant-pathogen interactions at the cellular and molecular level to create new resistant cultivars or to develop new plant protection products based on elicitation of plant…
Additional insights on the ecology of the relic tree Zelkova sicula di Pasquale, Garfì et Quézel (Ulmaceae) after the finding of a new population
2011
Abstract In early autumn 2009 a new population of Zelkova sicula, a very threatened tree species endemic to Sicily, has been found some 17 km east from the first and unique population previously known. The abiotic (slope, rock and stone outcrop cover, environmental stress, etc.) and biotic (plant species composition, vegetation mean height, total cover, etc.) features of 30 plots selected within the two populations were investigated in order to contribute at clarifying the actual and potential eco-geographic range of this species. Data analysis showed that the floristic differences among the sampled plots mostly relate to the rather high micro-habitat amplitude of the target species and the…
Modelling temperature-dependent dynamics of single and mixed infections in a plant virus
2022
Multiple viral infection is an important issue in health and agriculture with strong impacts on society and the economy. Several investigations have dealt with the population dynamics of viruses with different dynamic properties, focusing on strain competition during multiple infections and the effects on viruses’ hosts. Recent interest has been on how multiple infections respond to abiotic factors such as temperature (T). This is especially important in the case of plant pathogens, whose dynamics could be affected significantly by global warming. However, few mathematical models incorporate the effect of T on parasite fitness, especially in mixed infections. Here, we investigate simple mat…
Complex responses of global insect pests to climate change
2018
AbstractInsect pests strongly affect the productivity and profitability of agriculture and forestry. Despite the well-known sensitivity of insects to abiotic effects such as temperature, their potential responses to ongoing climate change remain unclear. Here we compile and review documented climate change responses of 31 of the globally most impactful phytophagous insect pests, focussing on species for which long-term, high-quality data are available. Most of the selected species show at least one response affecting their severity as pests, including changes in geographic range, population dynamics, life-history traits, and/or trophic interactions. Of the studied pests, 41% only show respo…