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51.
Janelle Quelch Ian T. Cameron 《Journal of Loss Prevention in the Process Industries》1994,7(6):463-473
It is generally acknowledged that there are substantial uncertainties present in any analysis of risk. This paper provides a brief overview of the current techniques used for uncertainty analyses, and highlights their inappropriateness for practical use in the complete risk assessment process. The concept of fuzzy sets as a means for quantifying uncertainty is introduced and a case study demonstrates the application of this method to a simple consequence analysis where parameter uncertainty is considered. The results of this fuzzy analysis are compared with those of a more traditional probabilistic approach using a Monte Carlo simulation. This comparison demonstrates that the novel approach of fuzzy sets is a more appropriate technique due to its non-statistical nature and that the amount of computation required is substantially reduced compared to the traditional probabilistic approach. The versatility of fuzzy set theory suggests that this approach could also be used to quantify other types of uncertainty present in the risk assessment process, including model uncertainty and expert opinion. 相似文献
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Meeghan?E.?GrayEmail author Elissa?Z.?Cameron Mary?M.?Peacock David?S.?Thain Veronica?S.?Kirchoff 《Behavioral ecology and sociobiology》2012,66(4):529-537
A growing number of studies conducted on diverse taxa have shown that extra-pair/group paternity is higher than what would
be predicted from behavioral observations alone. While it may be beneficial for females to mate with multiple males, this
often results in offspring not sired by the behavioral father, which could influence offspring survival, especially in social
mammals. Feral horses (Equus caballus) maintain stable social relationships over several years, usually with one stallion defending a harem band of unrelated mares
against other males. Sneak copulations by subordinate males have been observed and mares sometimes change bands, both of which
can result in foals sired by males other than the dominant band stallion. We measured female fidelity in free-ranging feral
horses in 23 bands, with 51 foals over four foaling seasons and tested offspring paternity against parental behaviors. We
used 12 polymorphic microsatellite loci and the program CERVUS 2.0 to determine and exclude potential sires. The majority
of mares remained in the band with the sire of their foal resulting in most foals being sired by the band stallion. Most foals
that were not sired by the band stallion were born in the year after a round-up and we could not determine if they were the
result of band changing or sneak copulations. Foals born into a band without their sire had lower survival rates and mothers
were significantly more protective of foals not sired by the band stallion. These findings suggest that band stability increases
the reproductive success of mares and support the importance of infanticide risk in equid social structure. 相似文献
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Busch J Dave R Hannah L Cameron A Rasolohery A Roehrdanz P Schatz G 《Conservation biology》2012,26(3):408-419
We examined the cost of conserving species as climate changes. We used a Maxent species distribution model to predict the ranges from 2000 to 2080 of 74 plant species endemic to the forests of Madagascar under 3 climate scenarios. We set a conservation target of achieving 10,000 ha of forest cover for each species and calculated the cost of achieving this target under each scenario. We interviewed managers of projects to restore native forests and conducted a literature review to obtain the net present cost per hectare of management actions to maintain or establish forest cover. For each species, we added hectares of land from lowest to highest cost per additional year of forest cover until the conservation target was achieved throughout the time period. Climate change was predicted to reduce the size of species' ranges, the overlap between species' ranges and existing or planned protected areas, and the overlap between species' ranges and existing forest. As a result, climate change increased the cost of achieving the conservation target by necessitating successively more costly management actions: additional management within existing protected areas (US$0-60/ha); avoidance of forest degradation (i.e., loss of biomass) in community-managed areas ($160-576/ha); avoidance of deforestation in unprotected areas ($252-1069/ha); and establishment of forest on nonforested land within protected areas ($802-2710/ha), in community-managed areas ($962-3226/ha), and in unprotected areas ($1054-3719/ha). Our results suggest that although forest restoration may be required for the conservation of some species as climate changes, it is more cost-effective to maintain existing forest wherever possible. 相似文献
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Landscape Assessment of the Degree of Protection of Alaska's Terrestrial Biodiversity 总被引:1,自引:0,他引:1
David Cameron Duffy § Keith Boggs Randall H. Hagenstein ‡ Robert Lipkin and Julie A. Michaelson 《Conservation biology》1999,13(6):1332-1343
Abstract: We assessed the degree to which Alaskan lands reflect the state's biodiversity by dividing the entire state into four categories of land protection ranging from highly protected to minimally protected in terms of potential for future development. We then compared the percentage of each ecoregion and plant-cover type in each land protection class. We assumed that 12% protection represents an acceptable minimum and examined the percentage of site records of rare plants in protected and unprotected areas. Of 28 ecoregions in Alaska, 15 (63.4%) have <12% of their area in highly protected areas. Similarly, 11 of 21 vegetation-cover types (43.7%) have <12% protection. For 32 rare vascular plants, an average of 27% of records occur on highly protected lands. Seventy-five percent of the rare plants had <50% of their records from highly protected lands. Less than 1% of Alaska has been permanently altered by human activity. In contrast to the lower 48 states, time remains to plan development that preserves biodiversity while permitting an economically sustainable economy—if the effort is made now. 相似文献
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E. Z. Cameron W. L. Linklater K. J. Stafford E. O. Minot 《Behavioral ecology and sociobiology》2000,47(4):243-249
In many mammalian species, female success in raising offspring improves as they age. The residual reproductive value hypothesis
predicts that each individual offspring will be more valuable to the mother as she ages because there is less conflict between
the current and potential future offspring. Therefore, as mothers age, their investment into individual offspring should increase.
Empirical evidence for an influence of declining residual reproductive value on maternal investment is unconvincing. Older
mothers may not invest more, but may be more successful due to greater experience, allowing them to target their investment
more appropriately (targeted reproductive effort hypothesis). Most studies do not preclude either hypothesis. Mare age significantly
influenced maternal investment in feral horses living on the North Island of New Zealand. Older mares, that were more successful
at raising foals, were more protective for the first 20 days of life, but less diligent thereafter. Total maternal input by
older mothers did not seem to be any greater, but was better targeted at the most critical period for foal survival and a
similar pattern was observed in mares that had lost a foal in the previous year. In addition, older mothers were more likely
to foal in consecutive years, supporting the hypothesis that they are investing less than younger mares in individual offspring.
Therefore, older mothers seem to become more successful by targeting their investment better due to experience, not by investing
more in their offspring.
Received: 22 September 1999 / Received in revised form: 30 October 1999 / Accepted: 6 November 1999 相似文献
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