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41.
The pink pigeon (Nesoenas mayeri) is an endemic species of Mauritius that has made a remarkable recovery after a severe population bottleneck in the 1970s to early 1990s. Prior to this bottleneck, an ex situ population was established from which captive-bred individuals were released into free-living subpopulations to increase population size and genetic variation. This conservation rescue led to rapid population recovery to 400–480 individuals, and the species was twice downlisted on the International Union for the Conservation of Nature (IUCN) Red List. We analyzed the impacts of the bottleneck and genetic rescue on neutral genetic variation during and after population recovery (1993–2008) with restriction site-associated sequencing, microsatellite analyses, and quantitative genetic analysis of studbook data of 1112 birds from zoos in Europe and the United States. We used computer simulations to study the predicted changes in genetic variation and population viability from the past into the future. Genetic variation declined rapidly, despite the population rebound, and the effective population size was approximately an order of magnitude smaller than census size. The species carried a high genetic load of circa 15 lethal equivalents for longevity. Our computer simulations predicted continued inbreeding will likely result in increased expression of deleterious mutations (i.e., a high realized load) and severe inbreeding depression. Without continued conservation actions, it is likely that the pink pigeon will go extinct in the wild within 100 years. Conservation rescue of the pink pigeon has been instrumental in the recovery of the free-living population. However, further genetic rescue with captive-bred birds from zoos is required to recover lost variation, reduce expression of harmful deleterious variation, and prevent extinction. The use of genomics and modeling data can inform IUCN assessments of the viability and extinction risk of species, and it helps in assessments of the conservation dependency of populations.  相似文献   
42.
An important consideration in conservation and biodiversity planning is an appreciation of the condition or integrity of ecosystems. In this study, we have applied various machine learning methods to the problem of predicting the condition or quality of the remnant indigenous vegetation across an extensive area of south-eastern Australia—the state of Victoria. The field data were obtained using the ‘habitat hectares’ approach. This rapid assessment technique produces multiple scores that describe the condition of various attributes of the vegetation at a given site. Multiple sites were assessed and subsequently circumscribed with GIS and remote-sensed data.  相似文献   
43.
The linear production of consumer goods is characterised by mass manufacture by multinational enterprises and globally dispersed supply chains. The current centralised model has created a distance between the manufacturer and end user, limiting the opportunity for intelligent circular approaches for production and consumption. Through a mixed method approach, opportunities of circularity are explored for the consumer goods sector. The study presents four lenses to analyse three enterprises through a multi-case study approach to explore the potential of digital intelligence and redistributed manufacturing (RDM) as enablers of circular business models. In addition, the study examines whether Discrete Event Simulation can be used to evaluate the circular scenarios identified through quantifying flows of material that determine traditional economic value (cost/tonne). The mixed method approach demonstrates that, a qualitative systemic analysis can reveal opportunities for circularity, gained through implementing ‘digital intelligence’ and distributed models of production and consumption. Furthermore, simulations can provide a quantified evaluation on the effects of introducing circular activities across a supply chain.  相似文献   
44.
Tanja Barth 《Chemosphere》1984,13(1):67-86
The concentration of oil derived material in the water column under an oil slick has been monitored. In an enclosed natural ecosystem the composition of the material in the water column was found, by liquid chromatography, to be dominated by polar degradation products, indicating that photooxidation of oil hydrocarbons is a major degradation pathway.  相似文献   
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46.
Participatory approaches to environmental decision making and assessment continue to grow in academic and policy circles. Improving how we understand the structure of deliberative activities is especially important for addressing problems in natural resources, climate change, and food systems that have wicked dimensions, such as deep value disagreements, high degrees of uncertainty, catastrophic risks, and high costs associated with errors. Yet getting the structure right is not the only important task at hand. Indeed, participatory activities can break down and fail to achieve their specific goals when some of the deliberators lack what we will call participatory virtues. We will argue for the importance of future research on how environmental education can incorporate participatory virtues to equip future citizens with the virtues they will need to deliberate about wicked, environmental problems. What is the role of education for deliberative skills and virtues relative to other aspects of environmental education, such as facts and values education? How important is it relative to careful design of the deliberative process? What virtues really matter?  相似文献   
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48.
The evolutionary stability of cooperation and altruism in colonies of social insects requires that nestmates be to some extent related. An efficient system of discrimination against non-nestmates protects the nest against unrelated conspecifics, which might exploit or parasitize the colony. The co-occurrence of unrelated individuals in mature colonies therefore is a rare event that deserves more attention. Here, we report on the relatively common incidence of colony fusion in the ant Platythyrea punctata. Workers of this ant can produce genetically identical female offspring from unfertilized eggs through thelytokous parthenogenesis. Consequently, the majority of colonies has a “clonal structure” and consists of individuals with identical multilocus genotypes. Nevertheless, field observations indicate that a surprisingly large percentage of colonies contain workers belonging to two or more different genetic lineages. Much of this genetic heterogeneity is incompatible with eventual recombination or mutation events, but instead appears to result from colony fusion or the adoption of unrelated individuals. Indeed, colonies of P. punctata from the Dominican Republic and Barbados readily merged in the laboratory and, after elimination of one of the two reproductive workers, formed stable, genetically heterogeneous colonies. We discuss the possible causes and benefits of colony fusion in natural populations.  相似文献   
49.
In efforts to evaluate the use of plants as a forensic tool for delineating contaminated soil and groundwater, a laboratory experiment and a field sampling effort were undertaken. Site assessments are often costly and inaccurate, requiring multiple mobilizations to hone in on source areas and getting accurate estimates of contaminant extent and distribution. As these extensive site delineations take place, valuable time and resources are lost. The findings of this study show that plants can be used as a tool to evaluate a variety of subsurface contaminants, either in the vadose zone or in the saturated zone. In the first field application of Taproot? Technology, a large, heavily forested site was sampled in one day and the contamination on‐site was more accurately delineated than had been generated at the site in over a decade, with more than 26 wells installed. New source zones were detected on the site, and the presence of new waste depositions was uncovered for the first time showing the great value of tree coring as a contaminant detection tool. © 2009 Wiley Periodicals, Inc.  相似文献   
50.
The relation of ambient levels of hydrocarbons to the products of atmospheric photochemistry has proved to be an elusive problem. Models to account for the photochemical processes are available based on laboratory examination of simulated atmospheres. Likewise, dispersion models are available which, for nonreacting species, can predict air quality given knowledge of emission rates and meteorological variables. However, integration of the dispersion model with the photochemical model is as yet an unsolved problem. In this study an empirical approach was applied in which the only assumption made was that there exists a relationship between early morning average hydrocarbon concentrations and subsequent maximum hourly average oxidant concentrations. A direct examination of all available days in several cities shows that, at any given hydrocarbon level, there exists a limit on the amount of oxidant which can be generated. Specifically it shows that the average 6:00–9:00 A.M. concentration of 0.3 ppm C nonmethane hydrocarbon can be expected to produce a maximum hourly average oxidant concentration of up to 0.1 ppm.  相似文献   
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