The majority of studies on environmental change focus on the response of single species and neglect fundamental biotic interactions, such as mutualism, competition, predation, and parasitism, which ...complicate patterns of species persistence. Under global warming, disruption of community interactions can arise when species differ in their sensitivity to rising temperature, leading to mismatched phenologies and/or dispersal patterns. To study species persistence under global climate change, it is critical to consider the ecology and evolution of multispecies interactions; however, the sheer number of potential interactions makes a full study of all interactions unfeasible. One mechanistic approach to solving the problem of complicated community context to global change is to (i) define strategy groups of species based on life-history traits, trophic position, or location in the ecosystem, (ii) identify species involved in key interactions within these groups, and (iii) determine from the interactions of these key species which traits to study in order to understand the response to global warming. We review the importance of multispecies interactions looking at two trait categories: thermal sensitivity of metabolic rate and associated life-history traits and dispersal traits of species. A survey of published literature shows pronounced and consistent differences among trophic groups in thermal sensitivity of life-history traits and in dispersal distances. Our approach increases the feasibility of unraveling such a large and diverse set of community interactions, with the ultimate goal of improving our understanding of community responses to global warming.
This study tested the hypothesis that soils with a deprived biodiversity due to metal pollution are less stable than non-polluted soils, containing a more diverse community. For this, soils were ...sampled from specific grasslands in the Netherlands that contain elevated heavy metal concentrations (Cu, Pb and Zn). Soils that showed the largest differences in metal concentrations were incubated in the laboratory using Terrestrial Model Ecosystems (TMEs). This approach enabled simultaneous measurement of structural (bacteria, nematodes, enchytraeids, earthworms) and functional parameters (nitrogen leaching, feeding activity, CO2 production, plant growth). The highest polluted soils showed a lower bacterial growth, and decreased enchytraeid and nematode biomass and diversity, hence a deprived community. More nitrate leached from high polluted soils, while all other functional endpoints did not differ. Additional stress application of zinc and heat was used to test the stability. Zinc treatment caused effects only in the higher polluted soils, observed at several moments in time for enchytraeids, CO2 fluxes and plant growth. Heat stress caused a large reduction in enchytraeid and earthworm biomass. Ammonium leaching was decreased by heat treatments in the most polluted soils, while CO2 was increased by heat in less polluted soils. Most effects were seen in the most polluted systems and it was concluded that they seem less stable.
Information indices from Ecosystem Network Analysis (ENA) can be used to quantify the development of an ecosystem in terms of its size and organization. There are two types of indices, i.e. absolute ...indices that describe both the size and organization of ecosystem (Total System Throughput (TST)—system size, Ascendancy (
A)—size of organized flows and Development Capacity (
C)—upper limit for
A, Overhead (
L)—size of unorganized flows) and relative indices that describe only the organization (Average Mutual Information (AMI
=
A:TST), Flow Diversity (
H
=
C:TST), Relative Overhead (RL
=
L:TST)).
It is theorized that environmental stress impair the ecosystem development and that the effect of stress can be quantified with the ENA information indices. Here we applied ENA on a case of environmental stress in a terrestrial ecosystem, i.e. soils that have endured long-term exposure to elevated copper concentration and altered pH.
The absolute indices showed an unexpected pattern of response to pollution, suggesting that ecosystems in polluted soils are more active and better organized than these in unpolluted soils. The relative indices, alternatively, responded to pollution as predicted by theory, i.e. with decrease of stress (pollution level) the level of specialization increased (increase of AMI) and losses of energy, e.g. due to respiration, decreased (decrease of Overhead). The diversity and evenness of flows showed hump-backed relationship with stress. Less polluted soils appeared to be less vulnerable to external disturbances and more efficient in processing energy (higher Relative Ascendancy (RA
=
A:
C)) than polluted soils. The relative information indices were rigid to changes in values of assumed parameters. The relative indices, opposite to absolute indices, appeared to be useful as indicators of environmental stress on the ecosystem level.
Many soil ecologists still encounter practical difficulties when extracting microarthropods from the soil. Methods using a humidity gradient, established by the use of a heat source, for collecting ...soil animals appeared not sufficiently efficient in case of sandy soils. For such type of soils, flotation techniques proved more suitable. The use of toxic or aggressive flotation fluids like kerosene, dibromo ethane, carbon tetrachloride and heptane, however, makes these methods less favourable. To circumvent this problem, a novel technique has been developed based on the flotation principle but using olive oil. The method uses a pumping system that injects olive oil at the base of a Perspex column in which the soil sample is suspended in water using a propeller. In this way, intensive contact between oil droplets and the organisms is established, increasing extraction efficiency. After stopping the propeller, animals can easily be collected from the oil floating to the water surface. Adding coloured mites to soil samples was used to determine extraction efficiency of the method. Average (±SD) recoveries of 82.7 ± 7.4% (
n = 34) and 89.7 ± 10.0% (
n = 10), respectively were obtained when extracting storage mites and predatory mites from a sandy soil.
Reducing decomposition and mineralization of organic matter by increasing groundwater levels is a common approach to reduce plant nutrient availability in many peat meadow restoration projects. The ...soil community is the main driver of these processes, but how community composition is affected by peat meadow restoration is largely unknown. Furthermore, it is unclear whether restoration induced changes could lead to altered decomposition and mineralization rates. We determined soil community composition in restored peat meadows with different groundwater levels and soil pH. This composition was subsequently used in food web model calculations of C and N mineralization rates to assess whether differences in soil community composition may have contributed to differences in decomposition and mineralization rates observed between these meadows.
Community composition of micro-organisms, Collembola and Enchytraeidae differed considerably between meadows and were correlated with differences in groundwater levels and soil pH. Collembolan and enchytraeid species from wet and neutral environments were more abundant at meadows with higher groundwater levels. Lower fungal to bacterial PLFA ratios and higher numbers of protozoa indicated an increased importance of the bacterial part of the food web at meadows with higher groundwater levels. Food web model calculations suggested that the observed changes in community composition would lead to higher rates of C and N mineralization at meadows with high groundwater levels. Results from modeling were consistent with field measurements of C mineralization, but not with measurements of N mineralization.
We conclude that understanding changes in soil community composition in response to specific restoration measures may help us to better understand ecosystem responses to wetland restoration schemes, especially regarding soil biogeochemical processes.
We have developed an efficient pretargeting strategy for renal cell carcinoma (RCC) based on a biologically produced bispecific monoclonal antibody (bs-mAb). Tumor targeting with this 2-step ...pretargeting strategy in the NU-12 mouse RCC model was very efficient compared with other pretargeting strategies, possibly due to unique characteristics of the NU-12 tumor used in our studies. Here we describe the bs-mAb G250xDTIn-1 pretargeting strategy in 3 different RCC nude mouse models.
Three different human RCC xenografts in nude mice (NU-12, SK-RC-1, and SK-RC-52 tumors) were pretargeted with 100 pmol bs-mAb G250xDTIn-1. Three days after administration of the bs-mAb, mice were injected intravenously with 4 pmol 111In-labeled bivalent peptide, diDTPA-FKYK (DTPA is diethylenetriaminepentaacetic acid). At 1, 4, 24, 48, and 72 h after injection of the radiolabeled peptide, the biodistribution of the radiolabel was determined. The 3 RCC tumors were characterized in vivo and in vitro for G250 antigen expression, vessel density, vascular volume, and vascular permeability and by targeting with 111In-/125I-labeled cG250 mAb.
Using the pretargeting strategy, relatively high uptake of the radiolabel was observed in all 3 tumor models (maximum uptake: SK-RC-1 278 +/- 130 %ID/g (percentage injected dose per gram), 1 h after injection > NU-12 93 +/- 41 %ID/g, 72 h after injection > SK-RC-52 54 +/- 9 %ID/g, 4 h after injection). Remarkably, uptake of the radiolabel in the tumor did not correlate with G250 antigen expression. The kinetics of the radiolabel in the tumor varied largely in the 3 RCC tumors: SK-RC-1 and SK-RC-52 tumors showed a washout of the 111In label from the tumor with time: only 30% of the radiolabel was retained in the tumor 3 d after injection, whereas the 111In label was fully retained in NU-12 tumors. Physiologic characteristics (vessel density, vascular volume, and vascular permeability) of the tumors may explain these differences.
G250 antigen-expressing tumors can be pretargeted very efficiently with the bs-mAb G250xDTIn-1. There was no correlation between G250 antigen expression and uptake of the radiolabel in the tumor using the pretargeting strategy or with directly labeled mAbs. Therefore, these studies show that physiologic characteristics of the tumor, such as vascular permeability, play a significant role in pretargeting.
TRENDS IN LINGUISTICS is a series of books that open new perspectives in our understanding of language. The series publishes state-of-the-art work on core areas of linguistics across theoretical ...frameworks, as well as studies that provide new insights by approaching language from an interdisciplinary perspective. TRENDS IN LINGUISTICS considers itself a forum for cutting-edge research based on solid empirical data on language in its various manifestations, including sign languages. It regards linguistic variation in its synchronic and diachronic dimensions as well as in its social contexts as important sources of insight for a better understanding of the design of linguistic systems and the ecology and evolution of language. TRENDS IN LINGUISTICS publishes monographs and outstanding dissertations as well as edited volumes, which provide the opportunity to address controversial topics from different empirical and theoretical viewpoints. High quality standards are ensured through anonymous reviewing. To discuss your book idea or submit a proposal, please contact Birgit Sievert.
