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561.
Genetic Structure of Fragmented Populations of the Endangered Daisy Rutidosis leptorrhynchoides 总被引:2,自引:0,他引:2
Abstract: The endangered grassland daisy Rutidosis leptorrhynchoides has been subject to severe habitat destruction and fragmentation over the past century. Using allozyme markers, we examined the genetic diversity and structure of 16 fragmented populations. The species had high genetic variation compared to other plant species, and both polymorphism and allelic richness showed strong positive relationships with log reproductive population size, reflecting a loss of rare alleles (frequency of q < 0.1) in smaller populations. Fixation coefficients were positively related to size, due either to a lack of rare homozygotes in small populations or to Wahlund effects (owing to spatial genetic structure) in large ones. Neither gene diversity nor heterozygosity was related to population size, and other population parameters such as density, spatial contagion, and isolation had no apparent effect on genetic variation. Genetic divergence among populations was low , despite a large north-to-south break in the species' current distribution. To preserve maximum genetic variation, conservation strategies should aim to maintain the five populations larger than 5000 reproductive plants, all of which occur in the north of the range, as well as the largest southern population of 626 plants at Truganina. Only one of these is currently under formal protection. High heterozygosity in smaller populations suggests that they are unlikely to be suffering from inbreeding depression and so are also valuable for conservation. Erosion of allelic richness at self-incompatibility loci, however, may limit the reproductive capacity of populations numbering less than 20 flowering plants. 相似文献
562.
This project used an internet survey of 287 Victorian drivers to quantify the extent to which drivers reportedly engage in a range of potentially distracting activities; the factors that influence their willingness to engage; and the strategies they use, if any, to manage distraction. Almost 60% of drivers use a mobile phone while driving and over one third use the phone in hand-held mode. A high proportion of drivers use audio entertainment systems, but relatively few use in-vehicle visual displays such as DVD players. Driver engagement in non-technology-based activities, such as eating, drinking, smoking and reading is also prevalent. Young drivers (18–25 yrs) were significantly more likely to report engaging in certain distracting activities, such as using a mobile phone, CD player and eating and drinking, than their middle-age (26–54 yrs) and older (55+ yrs) counterparts. Most drivers (84%) believe that their driving is less safe when engaged in distracting tasks and take steps to avoid distraction. The survey results provide valuable data to help target distraction policy and countermeasures that build upon the self-regulatory strategies already used by some drivers. 相似文献
563.
Implications of Land Use/Land Cover Change in the Buffer Zone of a National Park in the Tropical Andes 总被引:2,自引:0,他引:2
The impacts of land use and land cover (LULC) change in buffer zones surrounding protected ecological reserves have important
implications for the management and conservation of these protected areas. This study examines the spatial and temporal patterns
of LULC change along the boundary of Rio Abiseo National Park in the Northern Peruvian Andes. Landscape change within four
ecological zones was evaluated based on trends expected to occur between 1987 and 2001. Landsat TM and ETM imagery were used
to produce LULC classification maps for both years using a hybrid supervised/unsupervised approach. LULC changes were measured
using landscape metrics and from-to change maps created by post-classification change detection. Contrary to expectations,
tropical upper wet montane forest increased despite being threatened by human-induced fires and cattle grazing of the highland
grasslands inside the park. Within the park’s buffer zone, tropical moist forest remnants were fragmented into more numerous
and smaller patches between 1987 and 2001; this was in part due to conversion into agricultural land. The methods used in
this study provide an effective way to monitor LULC change detection and support the management of protected areas and their
surrounding environments. 相似文献
564.
A general theory known as the waste reduction (WAR) algorithm has been developed to describe the flow and the generation of potential environmental impact through a chemical process. The theory defines indexes that characterize the generation and the output of potential environmental impact from a process. The existing theory has been extended to include the potential environmental impact of the energy consumed in a chemical process. Energy will have both an environmental impact as well as an economic impact on process design and analysis. Including energy into the analysis of environmental impact is done by re-writing the system boundaries to include the power plant which supplies the energy being consumed by the process and incorporating the environmental effects of the power plant into the analysis. The effect of this addition on the original potential impact indexes will be discussed. An extensive engineering economic evaluation has been included in the process analysis which inherently contains the cost of the consumed energy as an operating cost. A case study is presented which includes a base process design and two modifications to the base design. Each design is analyzed from an economic perspective and an environmental impact perspective. The environmental impact analysis is partitioned into the impacts of the non-product streams and the impacts of the energy generation/consumption process. The comparisons of these analysis procedures illustrate the consequences for decision making in the design of environmentally friendly processes. 相似文献
565.
R H Young 《Journal - Water Pollution Control Federation》1972,44(6):1208-1211
566.
William B. Lord James F Booker David M. Getches Benjamin L. Harding Douglas S. Kenney Robert A. Young 《Journal of the American Water Resources Association》1995,31(5):939-944
ABSTRACT: This paper presents a summary of the findings and recommendations of the studies of severe, sustained drought reported in this special issue. The management facilities and institutions were found to be effective in protecting consumptive water users against drought, but much less effective in protecting nonconsumptive uses. Changes in intrastate water management were found to be effective in reducing the monetary value of damages, through reallocating shortages to low-valued uses, while only water banking and water marketing, among the possible interstate rule changes, were similarly effective. Players representing the basin states and the federal government in three gaming experiments were unable to agree upon and effect major changes in operating rules. The conclusions are (1) that nonconsumptive water uses are highly vulnerable to drought, (2) that consumptive uses are well-protected, (3) that drought risk is greatest in the Upper Basin, (4) that the Lower Basin suffers from chronic water shortage but bears little drought risk, (5) that opportunities exist for win-win rule changes, (6) that such rule changes are extremely difficult to make, and (7) that intrastate drought management is very effective m in reducing potential damages. 相似文献
567.
568.
569.
Removal of grease and oil by biological treatment processes 总被引:2,自引:0,他引:2
J C Young 《Journal - Water Pollution Control Federation》1979,51(8):2071-2087
570.
Genetic (allozyme) variation and population genetic structure of the rare shrub Daviesia suaveolens , found in only a few large populations on the eastern escarpment of the southern tablelands of New South Wales, were compared to those of its abundant and widespread relative D. mimosoides at both spatially equivalent and rangewide scales. We hypothesized that the rare species is genetically depauperate relative to the common one. We also generated baseline data on D. suaveolens to provide management recommendations for its conservation. Both species had high variation relative to other widespread woody angiosperms. Rangewide, the rare species exhibited lower species-level genetic variation than its common relative but a similar level of variation to that found in D. mimosoides over an equivalent spatial scale. Population-level genetic variation was similar for the two species. Over its small geographic range, D. suaveolens populations were three times as genetically differentiated as D. mimosoides over the same scale, showing a clear northsouth genetic disjunction and as much interpopulation divergence as the common species exhibited rangewide. These results confirm that not all types of rarity have the same genetic implications. Conservation strategies for D. suaveolens need not be concerned about low population-level variation unless populations become significantly smaller than is currently typical. Of more importance is to maintain the high interpopulation differentiation by conserving populations from both the north and south of the species' range. 相似文献