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821.
Cichlids are an excellent model to study explosive speciation and adaptive radiation. Their evolutionary success has been attributed to their ability to undergo rapid morphological changes related to diet, and their particular breeding biology. Relatively minor changes in morphology allow for exploitation of novel food resources. The importance of phenotypic plasticity and genetically based differences for diversification was long recognized, but their relationship and relative magnitude remained unclear. We compared morphology of individuals of four wild populations of the Lake Tanganyika cichlid Tropheus moorii with their pond-raised F(1) offspring. The magnitude of morphological change via phenotypic plasticity between wild and pond-bred F(1) fish exceeds pairwise population differences by a factor of 2.4 (mean Mahalanobis distances). The genetic and environmental effects responsible for among population differentiation in the wild could still be recognized in the pond-bred F(1) fish. All four pond populations showed the same trends in morphological change, mainly in mouth orientation, size and orientation of fins, and thickness of the caudal peduncle. As between population differentiation was lower in the wild than differentiation between pond-raised versus wild fish, we suggest the narrow ecological niche and intense interspecific competition in rock habitats is responsible for consistent shape similarity, even among long-term isolated populations. 相似文献
822.
Eddy J. Moors Annemarie Groot Hester Biemans Catharien Terwisscha van Scheltinga Christian Siderius Markus Stoffel Christian Huggel Andy Wiltshire Camilla Mathison Jeff Ridley Daniela Jacob Pankaj Kumar Suruchi Bhadwal Ashvin Gosain David N. Collins 《Environmental Science & Policy》2011,14(7):758-769
An ensemble of regional climate model (RCM) runs from the EU HighNoon project are used to project future air temperatures and precipitation on a 25 km grid for the Ganges basin in northern India, with a view to assessing impact of climate change on water resources and determining what multi-sector adaptation measures and policies might be adopted at different spatial scales.The RCM results suggest an increase in mean annual temperature, averaged over the Ganges basin, in the range 1–4 °C over the period from 2000 to 2050, using the SRES A1B forcing scenario. Projections of precipitation indicate that natural variability dominates the climate change signal and there is considerable uncertainty concerning change in regional annual mean precipitation by 2050. The RCMs do suggest an increase in annual mean precipitation in this region to 2050, but lack significant trend. Glaciers in headwater tributary basins of the Ganges appear to be continuing to decline but it is not clear whether meltwater runoff continues to increase. The predicted changes in precipitation and temperature will probably not lead to significant increase in water availability to 2050, but the timing of runoff from snowmelt will likely occur earlier in spring and summer. Water availability is subject to decadal variability, with much uncertainty in the contribution from climate change.Although global social-economic scenarios show trends to urbanization, locally these trends are less evident and in some districts rural population is increasing. Falling groundwater levels in the Ganges plain may prevent expansion of irrigated areas for food supply. Changes in socio-economic development in combination with projected changes in timing of runoff outside the monsoon period will make difficult choices for water managers.Because of the uncertainty in future water availability trends, decreasing vulnerability by augmenting resilience is the preferred way to adapt to climate change. Adaptive policies are required to increase society's capacity to adapt to both anticipated and unanticipated conditions. Integrated solutions are needed, consistent at various spatial scales, to assure robust and sustainable future use of resources. For water resources this is at the river basin scale. At present adaptation measures in India are planned at national and state level, not taking into account the physical boundaries of water systems. To increase resilience adaptation plans should be made locally specific. However, as it is expected that the partitioning of water over the different sectors and regions will be the biggest constraint, a consistent water use plan at catchment and river basin scale may be the best solution. A policy enabling such river basin planning is essential. 相似文献
823.
When food is limited and/or environmental conditions are unfavourable, many mammals reduce activity and use torpor to save
energy. Nevertheless, reliable predictors for torpor occurrence, especially in the wild, are currently not available. Interrelations
between torpor use and other energy conserving strategies are also poorly understood. We tested the hypothesis that reductions
in normothermic body temperature (T
b) and the period of activity before torpor events could be used as predictors for torpor occurrence in sugar gliders, Petaurus breviceps (body mass, ∼125 g), known to display daily torpor in the wild. Occurrence of torpor was preceded by significant (∼10–25%)
reductions of the duration of the activity phase. Moreover, the normothermic resting T
b fell by an average of 1.2°C over 3 days before a torpor event, relative to individuals that did not display torpor. Our new
findings suggest that before entering torpor, sugar gliders, which appear to use torpor as an emergency measure rather than
a routine energy saving strategy, systematically reduce activity times and normothermic resting T
bs to lower energy expenditure and perhaps to avoid employing torpor. Thus, reduced activity and normothermic T
b may provide a predictive tool for the occurrence of daily torpor in the wild. 相似文献
824.
A number of species (organic and inorganic) in airborne particulates cause the toxicity to living being. The potential of in vitro test methods were explored for toxicity assessment of trace toxic elements (inorganic species) present in ambient air on human being (lungs). A year long sampling of airborne particles (PM2.5) was carried (April 2008 to March 2009) in Lahore, Pakistan. A total of thirty nine samples were collected on 47 mm Zefluor Teflon filter membranes and each was analysed to characterize for the elements: Sb, As, Be, Cd, Cr, Co, Pb, Mn, Hg using ICP-MS in water extract and total acid digestate. The samples cytotoxicity was also established using lung derived cells and MTS colorimetric assays. This generated dose response curves and IC50 values for the elemental mixtures identified on the Teflon filter membrane. The results indicated that even at low concentrations airborne elemental mixtures displayed an additive toxic effect. 相似文献
825.
Fossils from the central Transantarctic Mountains in Antarctica are referred to a new species of the Triassic genus Kombuisia, one of four dicynodont lineages known to survive the end-Permian mass extinction. The specimens show a unique combination
of characters only present in this genus, but the new species can be distinguished from the type species of the genus, Kombuisia frerensis, by the presence of a reduced but slit-like pineal foramen and the lack of contact between the postorbitals. Although incomplete,
the Antarctic specimens are significant because Kombuisia was previously known only from the South African Karoo Basin and the new specimens extend the taxon’s biogeographic range
to a wider portion of southern Pangaea. In addition, the new finds extend the known stratigraphic range of Kombuisia from the Middle Triassic subzone B of the Cynognathus Assemblage Zone into rocks that are equivalent in age to the Lower Triassic Lystrosaurus Assemblage Zone, shortening the proposed ghost lineage of this taxon. Most importantly, the occurrence of Kombuisia and Lystrosaurus mccaigi in the Lower Triassic of Antarctica suggests that this area served as a refuge from some of the effects of the end-Permian
extinction. The composition of the lower Fremouw Formation fauna implies a community structure similar to that of the ecologically
anomalous Lystrosaurus Assemblage Zone of South Africa, providing additional evidence for widespread ecological disturbance in the extinction’s
aftermath. 相似文献
826.
Rahman A Seth D Mukhopadhyaya SK Brahmachary RL Ulrichs C Goswami A 《Die Naturwissenschaften》2009,96(1):31-38
Cellular interactions with engineered nanoparticles (NPs) are dependent on many properties, inherent to the nanoparticle (viz.
size, shape, surface characteristics, degradation, agglomeration/dispersal, and charge, etc.). Modification of the surface
reactivity via surface functionalization of the nanoparticles to be targeted seems to be important. Utilization of different
surface functionalization methods of nanoparticles is an emerging field of basic and applied nanotechnology. It is well known
that many disease-causing organisms induce host lipids and if deprived, their growth is inhibited in vivo. Amorphous nanosilica
(ANS) and amorphous microsilica with nanopores (AMS) were prepared by a combination of wet chemistry and high-energy ball
milling. Lipophilic moieties were attached to both ANS and AMS via chemical surface functionalization method. Lipophilic ANS
and AMS were found to inhibit the growth of Bombyx mori nuclear polyhedrosis virus (BmNPV) and chicken malarial parasites via absorption of silkworm hemolymph and chicken serum
lipids/lipoproteins, respectively, in vivo. Therefore, intelligent surface functionalization of NP is an important concept,
and its application in curing chicken malaria and BmNPV is presented here. Surface functionalization method reported in this
paper might serve as a valuable technology for treating many diseases where pathogens induce host lipid. 相似文献
827.
828.
Christian Hermans Ann C. Vandaele Michel Carleer Sophie Fally Réginald Colin Alain Jenouvrier Bernard Coquart Marie-France Mérienne 《Environmental science and pollution research international》1999,6(3):151-158
Absorption spectroscopy, which is widely used for concentration measurements of tropospheric and stratospheric compounds,
requires precise values of the absorption cross-sections of the measured species. NO2, O2 and its collision-induced absorption spectrum, and H2O absorption cross-sections have been measured at temperature and pressure conditions prevailing in the Earth’s atmosphere.
Corrections to the generally accepted analysis procedures used to resolve the convolution problem are also proposed. 相似文献
829.
Karl-Werner Schramm Petra Marth Alexander Wolf Klaus Hahn Konstantin Oxynos Johannes Schmitzer Antonius Kettrup 《Environmental Sciences Europe》1999,11(5):277-280
Measured partition coefficients (KLM/L) related to lipid-concentrations between the muscle (CML) and liver (CLL) tissue of two fish species (Abramis brama, Zoarces viviparus) exhibit nominal values of unity according the relationship KLM/L=CML/CLL=1 for persistent compounds such as highly chlorinated PCB and values above one for degradable compounds for example chlorinated cyclohexanes or DDT. The corresponding theory is presented. The relationship holds for samples for single fish as well as for pooled samples. 相似文献
830.
Christian N. Madu 《Journal of Environmental Planning and Management》1999,42(3):287-313
This paper presents a decision support framework for environmental planning in developing countries. The interest in protecting the natural environment from pollution gained increased importance in the 1990s with a push by world communities for sustainable development. Developing countries as well as the industrialized nations are expected to cut down on pollution and control the use of non-renewable natural resources. Although the concept of sustainable development sounds plausible, it is difficult to implement in many countries due to their conflicting goals. The world-wide targets on emissions, use of fossil fuels, reduction in water and atmospheric pollution require the participation of every nation. These goals are not easily achievable by some of the poorer developing countries partly because of their economic dependence on natural resources and partly because of their inability to afford more modern and efficient technologies. Thus, environmental planning goals are often in conflict with the development,social and economic needs of a country. In this paper, we develop a decision support framework that utilizes multicriteria and optimization models to address environmental planning problems. This framework is based on identifying the priorities of conflicting goals by working through and reducing the conflicts. A strategic planning framework is introduced into the decision support system since national planning is a strategic issue and these goals can only be achieved by adopting a systemic view. 相似文献