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Abstract: In April 1986, the endangered Perdido Key beach mouse (Peromyscus polionotus trissyllepsis) existed only as a small population of less than 30 animals on the western end of Perdido Key at Gulf State Park, Alabama This population was vulnerable to extinction from a variety of causes. Fifteen pairs of mice from Alabama were moved approximately 20 km on the same island to Gulf Islands National Seashore Florida between November 1986 and April 1988. The Alabama population was surveyed by live-trapping before each removal and showed a large increase during this study. Eleven pairs of mice were released into enclosures to stimulate burrowing and reduce dispersal at the release site. The last four pairs w e released unrestricted into the dune habitat Trapping in July 1988 revealed that virtually all available dune habitat (11,000 linear m; approximately 160 ha) had been occupied by the mice. Fifty-five individuals were captured including four of the released mice. Exchanges between the populations are recommended to prevent loss of genetic diversity. Future research should investigate demographics, dispersal pattern, and the application of DNA fingerprinting techniques to determine rates of gene flow in the population. The Perdido Key beach mouse provides an excellent model for studying the effects of a population bottleneck on genetic diversity and testing the predictions of population viability analysis.  相似文献   
2.
Abstract:  Biodiversity conservation on agricultural land is a major issue worldwide. We estimated separate and joint effects of remnant native woodland vegetation and recent tree plantings on birds on farms (approximately 500–1000 ha) in the heavily cleared wheat and sheep belt of southern Australia. Much of the variation (>70%) in bird responses was explained by 3 factors: remnant native-vegetation attributes (native grassland, scattered paddock trees, patches of remnant native woodland); presence or absence of planted native trees; and the size and shape of tree plantings. In terms of the number of species, remnant native vegetation was more important than tree planting, in a 3:1 ratio, approximately. Farms with high values for remnant native vegetation were those most likely to support declining or vulnerable species, although some individual species of conservation concern occurred on farms with large plantings. Farm management for improved bird conservation should account for the cumulative and complementary contributions of many components of remnant native-vegetation cover (e.g., scattered paddock trees and fallen timber) as well as areas of restored native vegetation.  相似文献   
3.
This work examines the effect of butanol (higher alcohol) on the emission pattern of neat neem oil biodiesel (NBD100) fueled diesel engine. Single-cylinder, 4-stroke, research diesel engine was employed to conduct the trial. Blends comprising the mixture of biodiesel and higher alcohol were prepared by employing an ultrasonic agitator. Four test fuels such as neat neem oil biodiesel, diesel, and two blends of higher alcohol/neem oil biodiesel: 10% and 20% (by volume). Experimental result showed that increasing alcohol content to biodiesel brought down the various emissions such as Smoke, NOx, HC, and CO by 6.8%, 10.4%, 8.6%, and 5.9%, respectively, at all loads. It was also concluded from the trail that a 20% higher alcohol/neem oil biodiesel blends show the promising signs in reducing all the emissions associated with biodiesel fuelled diesel engine.  相似文献   
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This paper examines the setting and evaluation of emergency rations for refugees and displaced people. After defining the purpose for which rations are designed, the variables affecting their quantification are discussed. The debate concerning the use of one as opposed to a range of energy levels for different populations is highlighted in a review of recent proposals for ration levels.
It is demonstrated that up to a twofold range occurs if different combinations of the main parameters are used. This has important implications for the large-scale provision of food. The use of one figure for the setting and evaluation of rations for all populations is inappropriate; figures should be set according to specific context and need. To achieve this, a practical two-stage approach is proposed. Stage 1, probably a desk exercise, uses pre-calculated 'look-up' tables which provide energy values for each country. These figures are for immediate use as 'rule-of-thumb' estimates, based on clearly defined parameters. The second stage involves refining the values using improved information on local conditions collected by field assessment.  相似文献   
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