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981.
Pei?Yang Zongbo?Li Yanqiong?Peng Darong?YangEmail author 《Die Naturwissenschaften》2012,99(3):199-205
In the obligate mutualism between figs (Ficus) and their specific pollinators (Chalcidoidea, Agaonidae), each species of fig wasp typically reproduces in figs of a single
host species. Host specificity is maintained largely because pollinators are attracted to tree-specific volatiles released
from their host figs, but whether the wasps can reproduce if they enter figs of non-host species is unclear. We investigated
the reproductive success of Ceratosolen emarginatus (associated with Ficus auriculata) and Ceratosolen sp. (associated with F. hainanensis) in atypical hosts by experimentally introducing foundresses into host and non-host figs. F. auriculata figs entered by Ceratosolen sp. were more likely to abort than if entered by C. emarginatus, but abortion of F. hainanensis figs was not affected by pollinator species. Single C. emarginatus foundresses produced more but smaller offspring in F. hainanensis than in their normal host. Conversely Ceratosolen sp. produced fewer but larger offspring in F. auriculata than in their normal host, probably as a result of having longer to develop. Mean style length differences, relative to the
lengths of the wasps’ ovipositors, may have dictated the number of offspring produced, with oviposition made easier by the
shorter styles in F. hainanensis figs. Our results imply that, in addition to morphological constraints and tree-specific volatiles, reduced reproductive
success in atypical hosts can be another factor maintaining host specificity, but for other species only behavioural changes
are required for host switching to occur. 相似文献
982.
Summary The balance of evidence suggests a perceptible human influence on global ecosystems. Human activities are affecting the global
ecosystem, some directly and some indirectly. If researchers could clarify the extent to which specific human activities affect
global ecosystems, they would be in a much better position to suggest strategies for mitigating against the worst disturbances.
Sophisticated statistical analysis can help in interpreting the influence of specific human activities on global ecosystems
more carefully. This study aims at identifying significant or influential human activities (i.e. factors) on CO2 emissions using statistical analyses. The study was conducted for two cases: (i) developed countries and (ii) developing
countries. In developed countries, this study identified three influential human activities for CO2 emissions: (i) combustion of fossil fuels, (ii) population pressure on natural and terrestrial ecosystems, and (iii) land
use change. In developing countries, the significant human activities causing an upsurge of CO2 emissions are: (i) combustion of fossil fuels, (ii) terrestrial ecosystem strength and (iii) land use change. Among these
factors, combustion of fossil fuels is the most influential human activity for CO2 emissions both in developed and developing countries. Regression analysis based on the factor scores indicated that combustion
of fossil fuels has significant positive influence on CO2 emissions in both developed and developing countries. Terrestrial ecosystem strength has a significant negative influence
on CO2 emissions. Land use change and CO2 emissions are positively related, although regression analysis showed that the influence of land use change on CO2 emissions was still insignificant. It is anticipated, from the findings of this study, that CO2 emissions can be reduced by reducing fossil-fuel consumption and switching to alternative energy sources, preserving exiting
forests, planting trees on abandoned and degraded forest lands, or by planting trees by social/agroforestry on agricultural
lands. 相似文献
983.
中国特色的城市化问题 总被引:13,自引:3,他引:13
针对当前社会经济发展中有中国特色的城市化建设问题,展开全方位、多视角的分析阐述,指出了认识对城市化问题的种种误区。提出中国的城市化发展应该与国情国力、工业化发展形势相协调,过程应有序、健康。并认为:(1)在相当长一段时间内、中国城市化水平以界定在50%-55%为宜,而不应该盲目追求西方国家不同国情的高指标、高比例;(2)对城市今后的发展规模应有稳步发展;(4)乡村城镇化必须发展生态农业与生态工业、走集约化、专业化的道路。正确引导中国的城市化进程,把城市发展和农村、工业和农业、人口流动、产业政策、区域平衡、科技进步、外向型经济可持续发展等当作整体一盘棋来统筹制定总体战略。 相似文献
984.
A.?R.?M.?Towfiqul?IslamEmail author Shuanghe?Shen Muhammed?Atikul?Haque Md.?Bodrud-Doza K.?W.?Maw Md.?Ahosan?Habib 《Environment, Development and Sustainability》2018,20(5):1935-1959
Sustainable groundwater quality is a key global concern and has become a major issue of disquiets in most parts of the world including Bangladesh. Hence, the assessment of groundwater quality is an important study to ensure its sustainability for various uses. In this study, a combination of multivariate statistics, geographical information system (GIS) and geochemical approaches was employed to evaluate the groundwater quality and its sustainability in Joypurhat district of Bangladesh. The results showed that the groundwater samples are mainly Ca–Mg–HCO3 type. Principal component analysis (PCA) results revealed that geogenic sources (rock weathering and cation exchange) followed by anthropogenic activities (domestic sewage and agro-chemicals) were the major factors governing the groundwater quality of the study area. Furthermore, the results of PCA are validated using the cluster analysis and correlation matrix analysis. Based on the groundwater quality index (GWQI), it is found that all the groundwater samples belong to excellent to good water quality domains for human consumption, although iron, fluoride and iodide contaminated to the groundwater, which do not pose any significant health hazard according to World Health Organization’s and Bangladesh’s guideline values. The results of irrigation water quality index including sodium adsorption ratio (SAR), permeability index and sodium percentage (Na %) suggested that most of the groundwater samples are good quality water for agricultural uses. The spatial distribution of the measured values of GWQI, SAR, Fe (iron), EC (electrical conductivity) and TH (total hardness) were spatially mapped using the GIS tool in the study area. 相似文献
985.
Degradation of azo dyes in water by Electro-Fenton process 总被引:19,自引:0,他引:19
Elodie?Guivarch Stephane?Trevin Claude?Lahitte Mehmet?A.?OturanEmail author 《Environmental Chemistry Letters》2003,1(1):38-44
The degradation of the azo dyes azobenzene, p-methyl red and methyl orange in aqueous solution at room temperature has been studied by an advanced electrochemical oxidation
process (AEOPs) under potential-controlled electrolysis conditions, using a Pt anode and a carbon felt cathode. The electrochemical
production of Fenton's reagent (H2O2, Fe2+) allows a controlled in situ generation of hydroxyl radicals (·OH) by simultaneous reduction of dioxygen and ferrous ions on the carbon felt electrode. In turn, hydroxyl radicals react
with azo dyes, thus leading to their mineralization into CO2 and H2O. The chemical composition of the azo dyes and their degradation products during electrolysis were monitored by high performance
liquid chromatography (HPLC). The following degradation products were identified: hydroquinone, 1,4-benzoquinone, pyrocatechol,
4-nitrocatechol, 1,3,5-trihydroxynitrobenzene and p-nitrophenol. Degradation of the initial azo dyes was assessed by the measurement of the chemical oxygen demand (COD). Kinetic
analysis of these data showed a pseudo-first order degradation reaction for all azo dyes. A pathway of degradation of azo
dyes is proposed. Specifically, the degradation of dyes and intermediates proceeds by oxidation of azo bonds and aromatic
ring by hydroxyl radicals. The results display the efficiency of the Electro-Fenton process to degrade organic matter.
Electronic Publication 相似文献
986.
Simas Angélica Mores Rúbia Steffens Juliana Dallago Rogério Marcos Kunz Airton Michelon William Fongaro Gislaine Viancelli Aline 《Environmental Chemistry Letters》2019,17(1):495-499
Environmental Chemistry Letters - Swine production generates large volumes of wastewater, rich in organic matter, nutrients and pathogens. Electrodisinfection is used to remove organic matter and... 相似文献
987.
The common occurrence of food transfers within human hunter–gatherer and forager–horticulturalist groups presents exciting test cases for evolutionary models of altruism. While kin biases in sharing are consistent with nepotism based on kin selection, there is much debate over the extent to which reciprocal altruism and tolerated scrounging provide useful explanations of observed behavior. This paper presents a model of optimal sharing breadth and depth, based on a general non-tit-for-tat form of risk-reduction based reciprocal altruism, and tests a series of predictions using data from Hiwi and Ache foragers. I show that large, high variance food items are shared more widely than small, easily acquired food items. Giving is conditional upon receiving in pairwise interactions and this correlation is usually stronger when the exchange of value rather than quantities is considered. Larger families and low producing families receive more and give less, consistent with the notion that marginal value may be a more salient currency than quantity.
相似文献
Michael GurvenEmail: Phone: +1-805-8932202 |
988.
Russell?Alpizar-JaraEmail author Kenneth?H.?Pollock Dawn?E.?Haines 《Environmental and Ecological Statistics》2005,12(2):155-168
The combined mark-recapture and line transect sampling methodology proposed by Alpizar-Jara and Pollock [Journal of Environmental and Ecological Statistics, 3(4), 311–327, 1996; In Marine Mammal Survey and Assessment Methods Symposium. G.W. Garner, S.C. Amstrup, J.L. Laake, B.F.J. Manly, L.L. McDonald, and D.C. Robertson (Eds.), A.A. Balkema, Rotterdam, Netherlands, pp. 99–114, 1999] is used to illustrate the estimation of population size for populations with prominent nesting structures (i.e., bald eagle nests). In the context of a bald eagle population, the number of nests in a list frame corresponds to a pre-marked sample of nests, and an area frame corresponds to a set of transect strips that could be regularly monitored. Unlike previous methods based on dual frame methodology using the screening estimator [Haines and Pollock (Journal of Environmental and Ecological Statistics, 5, 245–256, 1998a; Survey Methodology, 24(1), 79–88, 1998b)], we no longer need to assume that the area frame is complete (i.e., all the nests in the sampled sites do not need to be seen). One may use line transect sampling to estimate the probability of detection in a sampled area. Combining information from list and area frames provides more efficient estimators than those obtained by using data from only one frame. We derive an estimator for detection probability and generalize the screening estimator. A simulation study is carried out to compare the performance of the Chapman modification of the Lincoln–Petersen estimator to the screening estimator. Simulation results show that although the Chapman estimator is generally less precise than the screening estimator, the latter can be severely biased in presence of uncertain detection. The screening estimator outperforms the Chapman estimator in terms of mean squared error when detection probability is near 1 wheareas the Chapman estimator outperforms the screening estimator when detection probability is lower than a certain threshold value depending on particular scenarios. 相似文献
989.
Nadine C. Chapman Benjamin P. Oldroyd William O. H. Hughes 《Behavioral ecology and sociobiology》2007,61(8):1185-1194
Which task a social insect worker engages in is influenced by the worker’s age, genotype and the colony’s needs. In the honeybee,
Apis mellifera, genotype influences both the age a worker switches tasks and its propensity of engaging in specialist tasks, such as water
collecting, which only some workers will perform. In this study, we used colonies with natural levels of genetic diversity
and manipulated colony age demography to drastically increase the stimuli for the generalist tasks of foraging and nursing,
which all workers are thought to engage in at some point in their lives. We examined the representation of worker patrilines
engaged in nursing and foraging before and after the perturbation. The representation of patrilines among foragers and nurses
differed from that of their overall colony’s population. In the case of foraging, over- and underrepresentation of some patrilines
was not simply due to differences in rates of development among patrilines. We show that replacement foragers tend to be drawn
from patrilines that were overrepresented among foragers before the perturbation, suggesting that there is a genetic component
to the tendency to engage in foraging. In contrast, the representation of patrilines in replacement nurses differed from that
in the unperturbed nursing population. Our results show that there is a genetic influence on even the generalist tasks of
foraging and nursing, and that the way patrilines in genetically diverse colonies respond to increases in task stimuli depends
upon the task. The possible significance of this genetic influence on task allocation is discussed.
Electronic supplementary material Supplementary material is available in the online version of this article at doi: and is accessible to authorized users. 相似文献
990.
Ronald Fuge Ian M. S. Laidlaw William T. Perkins Kerry P. Rogers 《Environmental geochemistry and health》1991,13(2):70-75
The many abandoned base metal mines of the mid-Wales ore field are sources of extensive pollution. Some of the mineralised veins contain large amounts of pyrite and marcasite and oxidative weathering of these produces sulphuric acid resulting in very acidic mine drainage waters. In addition, the spoil tips associated with these mines can contain abundant iron sulphides. Drainage waters from these sources have pH values as low as 2.6 and are heavily contaminated with metals such as Al, Zn, Cd and Ni.Two of the main rivers of the area, the Rheidol and Ystwyth, intercept heavily contaminated acidic drainage which has a marked effect on water quality. The Rheidol contains over 100 g L–1 Zn for 16 km downstream of the acid water influx. This level is over three times the recommended EEC limit for Zn in salmonoid waters of low hardness. 相似文献