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排序方式: 共有434条查询结果,搜索用时 328 毫秒
281.
Roitberg BD Gillespie DR Quiring DM Alma CR Jenner WH Perry J Peterson JH Salomon M VanLaerhoven S 《Die Naturwissenschaften》2005,92(9):431-434
Evolutionary and ecological transitions from carnivorous to omnivorous feeding may be constrained by the ability of the animal
to cope with disparate types of foods, even if preadaptations for such behaviour exist. The omnivorous true bug, Dicyphus hesperus (Hemiptera: Miridae) requires both animals (small, soft-bodied insects) and plants in its diet and obtains the majority of
its dietary and metabolic water from plant feeding. Serrations on the lateral margins of the mandibular stylets wear with
age, and this wear is exacerbated when the insects feed on plants compared to those provided free water and no plants. D. hesperus that feed on plants attack fewer prey but consumed similar amounts of prey tissue compared to individuals that were provided
free water. Although others have shown mandible wear for plant-chewing animals we show for the first time that plant feeding
can impose similar wear on plant-piercing animals as well. 相似文献
282.
Michel Jan Niklas Cathy Trudinger Jason Lowe Ben Matthews Brd Romstad Christiano Pires de Campos Natalia Andronova 《Environmental Science & Policy》2005,8(6):614
This paper evaluates the influence of different policy-related and scientific choices on the calculated regional contributions to global climate change (the “Brazilian Proposal”). Policy-related choices include the time period of emissions, the mix of greenhouse gases and different indicators of climate change impacts. The scientific choices include historical emissions and model representations of the climate system. We generated and compared results of several simple climate models. We find that the relative contributions of different nations to global climate change—from emissions of greenhouse gases alone—are quite robust, despite the varying model complexity and differences in calculated absolute changes. For the default calculations, the average calculated contributions to the global mean surface temperature increase in 2000 are about 40% from OECD, 14% from Eastern Europe and Former Soviet Union, 24% from Asia and 22% from Africa and Latin America. Policy-related choices, such as time period of emissions, climate change indicator and gas mix generally have larger influence on the results than scientific choices. More specifically, choosing a later attribution start date (1990 instead of 1890) for historical emissions, decreases the contributions of regions that started emitting early, such as the OECD countries by 6 percentage points, whereas it increases the contribution of late emitters such as Asia by 8 percentage points. However, only including the fossil CO2 emissions instead of the emissions of all Kyoto gases (fossil and land use change), increases the OECD contributions by 21 percentage points and decreases the contribution of Asia by 14 percentage points. 相似文献
283.
Adenir V. Teodoro Andrea Muñoz Teja Tscharntke Alexandra-Maria Klein Jason M. Tylianakis 《Agriculture, ecosystems & environment》2011,140(1-2):14-19
Many tropical landscapes are today characterized by small forest patches embedded in an agricultural mosaic matrix. In such highly fragmented landscapes, agroforests have already been recognized as refuges for biodiversity but few studies have investigated the potential of non-forested land-use types to contribute to overall biodiversity of functionally important taxa in the tropics. This study experimentally investigated species richness, abundance, and community similarity of arthropods on Yellow Passion fruit plants, planted in standardized patches in 30 sites along a land-use intensity gradient. The gradient comprised all major land-use types of the area: forest fragments, abandoned coffee agroforests, coffee agroforests managed under shade trees, pastures, and rice fields in Coastal Ecuador. We found a total of 2123 individuals belonging to 242 species. Overall arthropod species richness increased with light intensity and leaf-surface area and decreased with land-use intensity: forest fragments and abandoned coffee agroforests harboured significantly more species than rice or pastures. Overall diversity in managed coffee agroforests was intermediate between the intensively managed and more natural habitats. However, the three most abundant taxa of arthropods (ants, spiders, and beetles) had the highest number of species in managed coffee agroforests, while ant abundance was highest in abandoned coffee agroforests and spider abundance highest in managed coffee agroforests. Analyses of community similarity revealed that open (pasture, and rice) and shaded (forest, abandoned and managed coffee agroforests) land-use types had distinct arthropod communities. In conclusion, although open agricultural land-use types tend to have fewer species in lower numbers, all land-use types contribute to overall biodiversity of the agricultural matrix because of distinct communities in shaded vs. non-shaded land-use types. 相似文献
284.
285.
Tristan?D.?PearceEmail author James?David?Ford Jason?Prno Frank?Duerden Jeremy?Pittman Maude?Beaumier Lea?Berrang-Ford Barry?Smit 《Mitigation and Adaptation Strategies for Global Change》2011,16(3):347-368
Climate is an important component of the operating environment for the Canadian mining sector. However, in recent years mines
across Canada have been affected by significant climatic hazards, several which are regarded to be symptomatic of climate
change. For the mining sector, climate change is a pressing environmental threat and a significant business risk. The extent
to which the mining sector is able to mitigate its own impact and adapt to climate change will affect its long-term success
and prosperity, and have profound economic consequences for host communities. This paper draws upon case studies conducted
with mining operations in Canada involving in-depth interviews with mining professionals and analysis of secondary sources
to characterize the vulnerability of the Canadian mining industry to climate change. Five key findings are discussed: i) mines
in the case studies are affected by climate events that are indicative of climate change, with examples of negative impacts
over the past decade; ii) most mine infrastructure has been designed assuming that the climate is not changing; iii) most
industry stakeholders interviewed view climate change as a minor concern; iv) limited adaption planning for future climate
change is underway; v) significant vulnerabilities exist in the post-operational phase of mines. This paper argues for greater
collaboration among mining companies, regulators, scientists and other industry stakeholders to develop practical adaptation
strategies that can be integrated into existing and new mine operations, including in the post-operational phase. 相似文献
286.
Houston Kempton Thomas A. Bloomfield Jason L. Hanson Patty Limerick 《Environmental Science & Policy》2010,13(6):558-566
Perpetual environmental management at operating and proposed hardrock mines is a rapidly expanding global dilemma. While economies of scale have encouraged larger mines, improved models routinely predict long-term water quality degradation at sulfide metal mines. Technical causes include oxidation of sulfide minerals and seepage from waste rock, tailings, and pit wall rock. Perpetual treatment is usually less expensive than permanent stabilization, even using 2% “risk-free” investment return rate; but this option greatly increases the social and financial complexity. A few regulations address perpetual management, but specific requirements range from formal acceptance to complete prohibition. With vague regulations, predictions of long-term impacts often delay permitting as operators and regulators grapple with model uncertainty and regulatory ambiguity. Risk management tools (e.g., insurance, inflation-protected investments, etc.) can reduce but cannot eliminate risk, and their continued availability is uncertain. What regulators and mine operators need – but do not have – is a clear framework to guide them in developing perpetual management plans that balance risks (e.g., uncertainty in predictions, cost, finance, and governance) and ensure responsible environmental and social stewardship. This paper responds with a review of perpetual mine management issues, including technical causes, policy examples, investment tools, case studies, technical remedies, and principles for successful long-term management. 相似文献
287.
Michelle P. Martín-Raugh Harrison J. Kell Jason G. Randall Cristina Anguiano-Carrasco Justin T. Banfi 《组织行为杂志》2023,44(1):132-156
What candidates say in an interview is important—but so is how they say it. We draw on dual-process theory to explain why interviewers rely on individuals' dynamic and static nonverbal cues to evaluate performance with quick, implicit inferences (System 1 processing). Yet, it remains unclear which cues most influence interviewers' judgments and whether moderators affecting interviewers' reliance on System 1 thinking (e.g., interview structure, modality, duration, and interviewee gender) impact the relationship between nonverbal cues and interview ratings. We performed the first meta-analysis to address these questions, integrating findings across 63 studies (N = 4868). The nonverbal cues demonstrating the strongest association with interview performance were professional appearance (ρ = .62), eye contact (ρ = .45), and head movement (ρ = .43). Moderator analyses highlight the persistent power of nonverbal cues, as the results were largely unaffected by interview structure, modality, or duration. Experimental design did play a role, as did interviewees' gender, with stronger effects for certain nonverbal cues (e.g., facial expressions and professional appearance) for women than men, conveying interviewers' reliance on gender-based stereotypes when judging their performance. Overall, these results suggest nonverbal cues and characteristics are an important influence on job applicants' success in employment interviews. 相似文献
288.
Why Economics Matters for Endangered Species Protection 总被引:3,自引:0,他引:3
Jason F. Shogren ‡‡‡ John Tschirhart Terry Anderson † Amy Whritenour Ando ‡ Steven R. Beissinger § David Brookshire Gardner M. Brown JR. †† Don Coursey ‡‡ Robert Innes §§ Stephen M. Meyer and Stephan Polasky††† 《Conservation biology》1999,13(6):1257-1261
Abstract: We offer three reasons why economics matters more to species protection than many people think and what this implies for the ongoing debate over the reauthorization of the Endangered Species Act of 1973. Economics matters because (1) human behavior generally, and economic parameters in particular, help determine the degree of risk to a species; (2) in a world of scarce resources, the opportunity cost of species protection—the costs of reduced resources for other worthwhile causes—must be taken into account in decision making; and (3) economic incentives are critical in shaping human behavior, and consequently the recovery of species. Endangered species protection that explicitly addresses these basic principles can avoid wasting valuable resources that yield no gain in species protection. 相似文献
289.
Nathan L. Kirk Jason P. Andras C. Drew Harvell Scott R. Santos Mary Alice Coffroth 《Marine Biology》2009,156(8):1609-1623
Numerous marine invertebrates form endosymbiotic relationships with dinoflagellates in the genus Symbiodinium. However, few studies have examined the fine-scale population structure of these symbionts. Here, we describe the genetic
structure of Symbiodinium type “B1/B184” inhabiting the gorgonian Gorgonia
ventalina along the Florida Keys. Six polymorphic microsatellite loci were utilized to examine 16 populations along the Upper, Middle,
and Lower Keys spanning a range of ~200 km. Multiple statistical tests detected significant differentiation in 54–92% of the
120 possible pairwise comparisons between localities, suggesting low levels of gene flow in these dinoflagellates. In general,
populations clustered by geographic region and/or reefs in close proximity. Some of the sharpest population differentiation
was detected between Symbiodinium from deep and shallow sites on the same reef. In spite of the high degree of population structure, alleles and genotypes
were shared among localities, indicating some connectivity between Symbiodinium populations associated with G. ventalina.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
290.
Invasive species richness often is negatively correlated with native species richness at the small spatial scale of sampling plots, but positively correlated in larger areas. The pattern at small scales has been interpreted as evidence that native plants can competitively exclude invasive species. Large-scale patterns have been understood to result from environmental heterogeneity, among other causes. We investigated species richness patterns among submerged and floating-leaved aquatic plants (87 native species and eight invasives) in 103 temperate lakes in Connecticut (northeastern USA) and found neither a consistently negative relationship at small (3-m2) scales, nor a positive relationship at large scales. Native species richness at sampling locations was uncorrelated with invasive species richness in 37 of the 60 lakes where invasive plants occurred; richness was negatively correlated in 16 lakes and positively correlated in seven. No correlation between native and invasive species richness was found at larger spatial scales (whole lakes and counties). Increases in richness with area were uncorrelated with abiotic heterogeneity. Logistic regression showed that the probability of occurrence of five invasive species increased in sampling locations (3 m2, n = 2980 samples) where native plants occurred, indicating that native plant species richness provided no resistance against invasion. However, the probability of three invasive species' occurrence declined as native plant density increased, indicating that density, if not species richness, provided some resistance with these species. Density had no effect on occurrence of three other invasive species. Based on these results, native species may resist invasion at small spatial scales only in communities where density is high (i.e., in communities where competition among individuals contributes to community structure). Most hydrophyte communities, however, appear to be maintained in a nonequilibrial condition by stress and/or disturbance. Therefore, most aquatic plant communities in temperate lakes are likely to be vulnerable to invasion. 相似文献