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201.
Bruce J. Eckholm Kirk E. Anderson Milagra Weiss Gloria DeGrandi-Hoffman 《Behavioral ecology and sociobiology》2011,65(5):1037-1044
Multiple mating by honeybee queens results in colonies of genotypically diverse workers. Recent studies have demonstrated
that increased genetic diversity within a honeybee colony increases the variation in the frequency of tasks performed by workers.
We show that genotypically diverse colonies, each composed of 20 subfamilies, collect more pollen than do genotypically similar
colonies, each composed of a single subfamily. However, genotypically similar colonies collect greater varieties of pollen
than do genotypically diverse colonies. Further, the composition of collected pollen types is less similar among genotypically
similar colonies than among genotypically diverse colonies. The response threshold model predicts that genotypic subsets of
workers vary in their response to task stimuli. Consistent with this model, our findings suggest that genotypically diverse
colonies likely send out fewer numbers of foragers that independently search for pollen sources (scouts) in response to protein
demand by the colony, resulting in a lower variety of collected pollen types. The cooperative foraging strategy of honeybees
involves a limited number of scouts monitoring the environment that then guide the majority of foragers to high quality food
sources. The genetic composition of the colony appears to play an important role in the efficiency of this behavior. 相似文献
202.
203.
Management of ecological reserve lands should rely on the best available science to achieve the goal of biodiversity conservation.
“Adaptive Resource Management” is the current template to ensure that management decisions are reasoned and that decisions
increase understanding of the system being managed. In systems with little human disturbance, certain management decisions
are clear; steps to protect native species usually include the removal of invasive species. In highly modified systems, however,
appropriate management steps to conserve biodiversity are not as readily evident. Managers must, more than ever, rely upon
the development and testing of hypotheses to make rational management decisions. We present a case study of modern reserve
management wherein beavers (Castor canadensis) were suspected of destroying habitat for endangered songbirds (least Bell’s vireo, Vireo bellii pusillus, and southwestern willow flycatcher, Empidonax traillii extimus) and for promoting the invasion of an exotic plant (tamarisk, Tamarix spp.) at an artificial reservoir in southern California. This case study documents the consequences of failing to follow
the process of Adaptive Resource Management. Managers made decisions that were unsupported by the scientific literature, and
actions taken were likely counterproductive. The opportunity to increase knowledge of the ecosystem was lost. Uninformed management
decisions, essentially “management by assertion,” undermine the long-term prospects for biodiversity conservation. 相似文献
204.
A framework for understanding ecological traps and an evaluation of existing evidence 总被引:10,自引:0,他引:10
When an animal settles preferentially in a habitat within which it does poorly relative to other available habitats, it is said to have been caught in an "ecological trap." Although the theoretical possibility that animals may be so trapped is widely recognized, the absence of a clear mechanistic understanding of what constitutes a trap means that much of the literature cited as support for the idea may be weak, at best. Here, we develop a conceptual model to explain how an ecological trap might work, outline the specific criteria that are necessary for demonstrating the existence of an ecological trap, and provide tools for researchers to use in detecting ecological traps. We then review the existing literature and summarize the state of empirical evidence for the existence of traps. Our conceptual model suggests that there are two basic kinds of ecological traps and three mechanisms by which traps may be created. To this point in time, there are still only a few solid empirical examples of ecological traps in the published literature (although those few examples suggest that both types of traps and all three of the predicted mechanisms do exist in nature). Therefore, ecological traps are either rare in nature, are difficult to detect, or both. An improved library of empirical studies will be essential if we are to develop a more synthetic understanding of the mechanisms that can trigger maladaptive behavior in general and the specific conditions under which ecological traps might occur. 相似文献
205.
Sedinger JS Ward DH Schamber JL Butler WI Eldridge WD Conant B Voelzer JE Chelgren ND Herzog MP 《Ecology》2006,87(1):151-159
Climate in low-latitude wintering areas may influence temperate and high-latitude breeding populations of birds, but demonstrations of such relationships have been rare because of difficulties in linking wintering with breeding populations. We used long-term aerial surveys in Mexican wintering areas and breeding areas in Alaska, USA, to assess numbers of Black Brant (Branta bernicla nigricans; hereafter brant) on their principal wintering and breeding area in El Ni?o and non-El Ni?o years. We used Pollock's robust design to directly estimate probability of breeding and apparent annual survival of individually marked brant at the Tutakoke River (TR) colony, Alaska, in each year between 1988 and 2001. Fewer brant wintered in Mexico during every El Ni?o event since 1965. Fewer brant were observed on the principal breeding area following each El Ni?o since surveys began in 1985. Probability of breeding was negatively related to January sea surface temperature along the subtropical coast of North America during the preceding winter. Between 23% (five-year-olds or older) and 30% (three-year-olds) fewer brant nested in 1998 following the strong El Ni?o event in the winter of 1997-1998 than in non-El Ni?o years. This finding is consistent with life history theory, which predicts that longer-lived species preserve adult survival at the expense of reproduction. Oceanographic conditions off Baja California, apparently by their effect on Zostera marina (eelgrass), strongly influence winter distribution of brant geese and their reproduction (but not survival), which in turn affects ecosystem dynamics in Alaska. 相似文献
206.
Evaluating the vulnerability of surface waters to antibiotic contamination from varying wastewater treatment plant discharges 总被引:8,自引:0,他引:8
Effluents from three wastewater treatment plants with varying wastewater treatment technologies and design were analyzed for six antibiotics and caffeine on three sampling occasions. Sulfamethoxazole, trimethoprim, ciprofloxacin, tetracycline, and clindamycin were detected in the effluents at concentrations ranging from 0.090 to 6.0 microg/L. Caffeine was detected in all effluents at concentrations ranging from 0.19 to 9.9 microg/L. These findings indicate that several conventional wastewater management practices are not effective in the complete removal of antibiotics, and their discharges have a large potential to affect the aquatic environment. To evaluate the persistence of antibiotics coming from the wastewater discharges on the surrounding surface waters, samples were collected from the receiving streams at 10-, 20- and 100-m intervals. Ciprofloxacin, sulfamethoxazole, and clindamycin (0.043 to 0.076 microg/L) were found as far as 100 m from the discharge point, which indicates the persistence of these drugs in surface waters. 相似文献
207.
Hay KJ Johnsen BE Ginochio PR Cooper JA 《Journal of the Air & Waste Management Association (1995)》2006,56(5):657-665
The relative accuracy (RA) of a newly developed mercury continuous emissions monitor, based on X-ray fluorescence, was determined by comparing analysis results at coal-fired plants with two certified reference methods (American Society for Testing and Materials [ASTM] Method D6784-02 and U.S. Environment Protection Agency [EPA] Method 29). During the first determination, the monitor had an RA of 25% compared with ASTM Method D6784-02 (Ontario Hydro Method). However, the Ontario Hydro Method performed poorly, because the mercury concentrations were near the detection limit of the reference method. The mercury in this exhaust stream was primarily elemental. The second test was performed at a U.S. Army boiler against EPA Reference Method 29. Mercury and arsenic were spiked because of expected low mercury concentrations. The monitor had an RA of 16% for arsenic and 17% for mercury, meeting RA requirements of EPA Performance Specification 12a. The results suggest that the sampling stream contained significant percentages of both elemental and oxidized mercury. The monitor was successful at measuring total mercury in particulate and vapor forms. 相似文献
208.
209.
Anik Lambert-Bélanger Sacha Dubois Bruce Weaver Nadia Mullen Michel Bédard 《Journal of Safety Research》2012,43(5-6):333-338
IntroductionWe wished to determine the extent to which number of passengers, driver age, and sex were associated with aggressive driving actions (ADAs) in young drivers involved in a fatal crash.MethodsWe used U.S. fatal-crash data from Fatality Analysis Reporting System (FARS), 1991 –2008. Proxy measures of aggressive driving included ADA presence and speed differential (posted speed limit minus estimated travel speed). We examined the odds of an ADA and speed differential in young drivers (aged 16 to 25) by passenger status.ResultsCompared to driving alone young drivers (aged 16) had increased odds of an ADA between 14% (OR: 1.14; 95% CI: 1.07; 1.22) and 95% (OR: 1.95; 95% CI: 1.40; 2.74) when accompanied by one and five passengers, respectively. Further, carrying a higher number of passengers was a stronger predictor of speeding in younger drivers.ConclusionsThis study supports the use of graduated licensing approaches. Specifically, developing interventions to reduce aggressive driving appear imperative.Impact on IndustryWhile the results of our study support the use of graduated licensing approaches there is room for improvement. Our study indicates that tackling impaired driving is not sufficient to drastically reduce aggressive driving among the youngest drivers. Further research on young drivers is required to understand the influence of peers and the role of gender on driving behavior. Strategies to reduce aggressive driving behaviors among the youngest drivers may not only prevent crashes during their early driving careers but may also translate into a reduced crash risk over their lifetime. 相似文献
210.
Health institutions in the People's Republic of China are under considerable challenge. Innovations in management systems may support the challenge to increase both efficiency and effectiveness. The balanced scorecard (BSC) is one such innovation. We have used a model to explore the factors that may impact the diffusion of the BSC in Chinese government hospitals. In particular, we concentrate on three factors - the outer context, the nature of the innovation and the communication and influence. The outer context and the nature of the innovation do provide an inducement to implement a BSC. The strength of the communication and influence may affect the level of take-up. However, we recognise that they may choose "the BSC not for any apparent technical excellence but for the legitimation that Western management practices may bring to local managers. 相似文献