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231.
Time budgets and foraging in a Malagasy primate: do sex differences reflect reproductive condition and female dominance? 总被引:5,自引:0,他引:5
Claire A. Hemingway 《Behavioral ecology and sociobiology》1999,45(3-4):311-322
Female mammals commonly employ behavioral tactics of modulating activity levels and foraging behavior to counter the energetic
burden of reproduction; these behavioral changes are reflected as intersexual differences. Traditional views of Malagasy primates
posit that high reproductive costs select for female dominance which guarantees to energetically stressed females priority
of resource access. I tested predictions regarding reproductive influences on sex differences in time budgets and foraging
behavior using two groups of Milne-Edwards' sifaka (Propithecus diadema edwardsi) in southeastern Madagascar. Compared to males, females increased neither feeding nor resting time during gestation or lactation.
Sex differences were essentially absent in all foraging time variables examined (time, duration, rate). In contrast, dietary
composition diverged between the sexes in some months. The possibility that females selected particular food items to boost
nutrient and energetic intake to meet increased requirements during reproduction must be further clarified with nutritional
analyses. Sex differences in plant part choices coincided with lactation in one of the two study groups. Thus, the timing
of sex differences in feeding patterns of P. d. edwardsi only partially supports the prediction that sex differences are most pronounced during the period of greatest female energetic
demand. A comparative review indicated no tight association between female dominance and sex differences in foraging among
Malagasy primates. Traditional female dominance theory falls short of explaining the observed patterns. The results of my
study coupled with recent evidence suggest that non-behavioral tactics involving energy conservation and storage require further
attention as mechanisms by which female lemurs cope with reproductive costs.
Received: 12 June 1998 / Accepted after revision: 10 October 1998 相似文献
232.
Green TJ Reeves CE Fleming ZL Brough N Rickard AR Bandy BJ Monks PS Penkett SA 《Journal of environmental monitoring : JEM》2006,8(5):530-536
This paper describes a new dual-channel PEroxy RadiCal Amplification (PERCA) instrument, which has been designed to improve the time resolution and signal to noise and to reduce the interference caused by variations in ambient ozone concentrations. The instrument was run at the Weybourne Atmospheric Observatory (WAO), North Norfolk, during WAOWEX (Weybourne Atmospheric Observatory Winter Experiment) in January/February 2002 and INSPECTRO (Influence of clouds on the spectral actinic flux in the lower troposphere) in September 2002. The performance of the instrument is assessed and compared to that of a single channel instrument. In particular, it is shown how the precision is greatly improved in fluctuating background ozone conditions. In addition the improved time response of the instrument allows changes in peroxy radical concentrations to be related to rapid changes in nitric oxide concentrations and the ozone photolysis frequency, j(O(1)D). 相似文献
233.
Ideally, the response of electrochemical detectors is proportional to the concentration of targeted airborne chemicals and is not be affected by concomitantly present substances. Manufacturers provide a limited list of cross-sensitivities but end-users have anecdotally reported unexpected interferences by other substances. Electrochemical detectors designed to measure airborne levels of CO, H(2)S, NO, NO(2), or SO(2), were challenged with potentially interfering substances in the absence of target analytes. Cross-sensitivities undocumented by the manufacturers were observed and were found to vary between different models of instruments for the same challenge chemical. 相似文献
234.
This paper examines the influence of dune morphological evolution on plant species diversity and composition on the Magheramore
dune system, Donegal, north-west Ireland. It aims to demonstrate the need for understanding of local geomorphological factors
and their affect on ecological processes for the enhanced conservation management of coastal dunes. Vegetation surveys and
cluster analysis of species associations, in combination with GIS analysis focused on two prograding dune sites within the
Magheramore system. Contrasting geomorphic evolution over similar timescales has imposed site-specific environmental conditions
that have had a direct impact on the range of plant species communities present. Cluster analysis revealed 5 main species
community types that defined specific dune habitats, the organisation of which is strongly influenced by geomorphic evolution.
This study demonstrates the importance of geomorphic evolution and morphological heterogeneity in habitat and species diversity. 相似文献
235.
Claggett PR Jantz CA Goetz SJ Bisland C 《Environmental monitoring and assessment》2004,94(1-3):129-146
Natural resource lands in the Chesapeake Bay watershed are increasingly susceptible to conversion into developed land uses, particularly as the demand for residential development grows. We assessed development pressure in the Baltimore-Washington, DC region, one of the major urban and suburban centers in the watershed. We explored the utility of two modeling approaches for forecasting future development trends and patterns by comparing results from a cellular automata model, SLEUTH (slope, land use, excluded land, urban extent, transportation), and a supply/demand/allocation model, the Western Futures Model. SLEUTH can be classified as a land-cover change model and produces projections on the basis of historic trends of changes in the extent and patterns of developed land and future land protection scenarios. The Western Futures Model derives forecasts from historic trends in housing units, a U.S. Census variable, and exogenously supplied future population projections. Each approach has strengths and weaknesses, and combining the two has advantages and limitations. 相似文献
236.
Rose M Harrison N Greaves A Dowding A Runacres S Gem M Fernandes A White S Duff M Costley C Leon I Petch RS Holland J Chapman A 《Journal of environmental monitoring : JEM》2005,7(4):378-383
To control the outbreak of foot and mouth disease, which occurred in the UK in early 2001, a large number of farm animals were slaughtered. Where it was not possible to render or landfill the carcasses, they were destroyed by burning on open pyres, with wood, coal and other materials. Uncontrolled combustion such as this is known to produce small quantities of dioxins and an investigation was made into whether, as a result of the burning, there was an elevation in the concentrations of these compounds in food produced in the areas close to the pyres. With few exceptions, concentrations of PCDD/Fs and PCBs were within the expected ranges as predicted by reference data. No accumulation over time was evident from a repeat milk sampling exercise. Where elevated concentrations of PCDD/Fs and PCBs were found in chickens and eggs, they were in samples not destined for the food chain. Elevated levels in some samples of milk from Dumfries and Galloway were not found in earlier or later samples and may have been found as a result of a temporary feeding regime. Elevated concentrations in lamb from Carmarthenshire were from very young animals which would not have entered the food chain. There was no evidence of any significant increase in dietary exposure to PCDD/Fs and PCBs as a result of the FMD pyres. 相似文献
237.
Zoe O’Hara Claire Crossan John Craft Linda Scobie 《Food and environmental virology》2018,10(2):217-221
Shellfish samples (n = 310) purchased from local supermarkets were analysed for the presence of hepatitis E virus (HEV) by nested RT-PCR and real-time qRT-PCR. Overall, 2.9% of samples tested positive for the presence of HEV. Phylogenetic analysis of HEV sequences revealed all as being genotype 3 HEV. This is the first report of the detection of HEV in commercially sold shellfish in Scotland. These findings may encourage further research that will help address the gaps in the knowledge in respect to foodborne transmission of HEV in Scotland and the rest of the United Kingdom. 相似文献
238.
Claire H. Sink Karen M. Adams Brian B. Looney Karen M. Vangelas Norman H. Cutshall 《补救:环境净化治理成本、技术与工艺杂志》2004,15(1):89-98
The U.S. Department of Energy is conducting a project to accelerate remediation through the use of monitored natural attenuation and enhanced attenuation for chlorinated ethenes in soils and groundwater. Better monitoring practices, improved scientific understanding, and an advanced regulatory framework are being sought through a team effort that engages technology developers from academia, private industry, and government laboratories; site cleanup managers; stakeholders; and federal and state regulators. The team works collaboratively toward the common goals of reducing risk, accelerating cleanup, reducing cost, and minimizing environmental disruption. Cutting‐edge scientific advances are being combined with experience and sound environmental engineering in a broadly integrated and comprehensive approach that exemplifies socalled “third‐generation R&D.” The project is potentially a model for other cleanup activities. © 2004 Wiley Periodicals, Inc. 相似文献
239.
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